CN105676516A - Display device and method of driving the same - Google Patents

Abstract

The present invention provides a display device and a method for driving the display device. According to the embodiments, power consumption can be suppressed as a whole without greatly reducing transmission efficiency. According to an embodiment, the display device has: a plurality of sub-pixels (PX) arranged along a first direction and a second direction crossing the first direction, a color filter corresponding to each sub-pixel (PX), and an illumination device (LU). Furthermore, the color filters are at least adjacent to a blue filter and a yellow filter, and the lighting device has at least a cyan light output period and a magenta light output period within one frame period.

Description

Display device, driving method of display device

Cross References to Related Applications

This application is based upon and claims the benefit of priority from prior Japanese Patent Applications No. 2014-247904 filed on December 8, 2014 and No. 2015-222143 filed on November 12, 2015, the entire contents of which are incorporated in This is for reference.

technical field

This embodiment relates to a display device and a method for driving the display device.

Background technique

In recent years, portable terminals are becoming increasingly popular. Portable terminals include smart phones, personal digital assistants (PDAs) or tablet PCs, etc., and their display performance is also being enhanced. These portable terminals are capable of displaying color images.

As a technique for displaying color images, there is a field sequential color (FSC) method. Conventionally, the FSC method uses a red (R) light emitting device, a green (G) light emitting device, and a blue (B) light emitting device as lighting devices. In the FSC method, one frame period is divided into three periods (also referred to as the light-emitting period of the red (R) light-emitting device, the light-emitting period of the green (G) light-emitting device, and the light-emitting period of the blue (B) light-emitting device. for three fields). Then, pixels selected for red display (selected R pixels), pixels selected for blue display (selected B pixels) corresponding to each of three (R, G, B) fields, Pixels selected for green display (selected G pixels). In addition, as the light emitting device, a point light source can be used. More specifically, light emitting diodes (LEDs) can be used as the point light sources.

The above-mentioned selected R pixel, selected B pixel, and selected G pixel are pixels corresponding to R, G, and B signals selected from a plurality of pixels arranged two-dimensionally on the liquid crystal display panel. Each liquid crystal display image composed of the selected R pixel, the selected B pixel, and the selected G pixel is displayed in an independent period, but the color image is visually recognized by humans due to the afterimage effect of the eyes. In the above-mentioned FSC method, since no color filter is required on the liquid crystal display panel, the utilization rate of light is high.

Contents of the invention

A display device according to one aspect of the present invention has: a plurality of sub-pixels arranged along a first direction and a second direction crossing the first direction; a color filter corresponding to each sub-pixel; and an illumination device, the filter The color chip includes at least an adjacent blue filter and a yellow filter, the lighting device has a light source, and a frame period of light output from the light source has at least a period of cyan light output and a period of magenta light output .

Another aspect of the present invention is a method for driving a display device, wherein the display device has: a plurality of sub-pixels arranged along a first direction and a second direction intersecting the first direction, a filter corresponding to each sub-pixel A color chip and an illuminating device, the color filter at least includes an adjacent blue filter and a yellow filter, and the illuminating device outputs at least cyan light and magenta light in one frame period.

Description of drawings

FIG. 1 is an exploded perspective view schematically showing a configuration example of a liquid crystal display device LCD in this embodiment.

FIG. 2 is a diagram schematically showing the structure and equivalent circuit of the liquid crystal display panel PNL.

FIG. 3A is a diagram illustrating an arrangement example of color filters of sub-pixels and an example of colors of the lighting device.

FIG. 3B is a graph showing the relationship of the luminescent colors output from the color filters with respect to the cyan field and the magenta field within one frame period of the lighting device.

3C is a graph showing an example of the intensity of the luminescent color output from the color filter with respect to the cyan field and the magenta field of the lighting device.

FIG. 4A is a diagram illustrating another example of the arrangement of color filters of sub-pixels and the color of the lighting device.

4B is a diagram showing the relationship of the luminescent colors output from the color filters with respect to the cyan field, the white field, and the magenta field within one frame period of the lighting device.

4C is a graph showing an example of the intensity of the luminous color output from the color filter with respect to the cyan field, the white field, and the magenta field of the lighting device.

5 is a graph showing the transmittance of a blue filter and a yellow filter, and light emission energy of a blue (B) LED, a green (G) phosphor, and a red (R) phosphor.

6 is a comparison of the aperture ratio and transmittance of the sub-pixel with the yellow filter and the sub-pixel with the blue filter in one embodiment with the aperture ratio and transmittance of the sub-pixel without the filter And shown in the figure.

7A shows the relationship between the luminance and current of the LED of R, the LED of G, and the LED of B, and the phosphor LED (coated with white (W) light-emitting LED) when the multiplication result of the luminance and current is defined as 100. A graph showing the multiplication result of luminance and current, and further defining the multiplication result as an LED effect.

7B is a graph comparing the aperture ratio, transmittance, and LED effect of the embodiment of the present application with those of the conventional field sequential method.

8A is an explanatory diagram showing the distance of color change on a chromaticity diagram in the case where a display color changes over an area including primary colors R, G, and B. FIG.

8B is an explanatory diagram showing the distance of color change on the chromaticity diagram in the case where the display color changes over the regions of cyan and magenta.

9A is a timing chart showing another embodiment and an operation when the lighting device has a white (W) light emitting field in addition to a cyan light emitting field and a magenta light emitting field.

Fig. 9B shows yet another embodiment and the lighting device has a white (W) luminous field in addition to a cyan luminous field and a magenta luminous field, and the filter also has yellow, blue, white (W) luminous fields. ) time chart of the operation of the filter case.

FIG. 10A is a diagram showing an embodiment in a case where a filter includes white (W), yellow (Y), and blue (B).

FIG. 10B is a diagram illustrating an example of a pixel circuit corresponding to the filter of FIG. 10A .

FIG. 11A is a diagram illustrating another embodiment in which the filter includes white (W), yellow (Y), and blue (B).

FIG. 11B is a diagram illustrating an example of a pixel circuit corresponding to the filter of FIG. 11A .

FIG. 11C is a diagram illustrating another example of a pixel circuit corresponding to the filter of FIG. 11A .

FIG. 12A is a diagram showing another embodiment of a case where the filter includes white (W), yellow (Y), and blue (B).

FIG. 12B is a diagram illustrating an example of a pixel circuit corresponding to the filter of FIG. 12A .

FIG. 12C is a diagram illustrating another example of a pixel circuit corresponding to the filter of FIG. 12A .

FIG. 13 is a graph showing an example of a graph of the spectral transmittance of a yellow filter and a blue filter.

FIG. 14 is a diagram showing a calculation example of the area ratio of the yellow filter and the blue filter.

FIG. 15 is a graph showing a characteristic example of spectral luminance when a magenta LED and a cyan LED of the lighting device are simultaneously made to emit light.

Fig. 16 uses the spectral transmittance of the two filters shown in Fig. 13, the area ratio of the two filters shown in Fig. 14 and the spectral brightness shown in Fig. Graph showing the relationship between the transmittance ratio of the color filter and the yellow filter and the luminance ratio of the magenta and cyan lighting devices.

detailed description

Hereinafter, various embodiments will be described with reference to the drawings.

First, the introduction of the embodiment described below will be described. Since the FSC method does not require a color filter on the liquid crystal display panel, the utilization rate of light is high. However, the luminous efficiency of the green (G) LED is about 1/3 of that of the blue (B) LED. If the supply voltage is increased in order to increase the luminous efficiency of the green (G) LED, there is a problem that power consumption increases. In addition, in the case of a red (R) LED, the wavelength related to chromaticity tends to change over time. In order to maintain the white area on the chromaticity diagram, it is necessary to use the red (R) LED To adjust the chromaticity of the green (G) LED and the blue (B) LED. However, this adjustment involves technical difficulties.

In addition, there is a problem that color break-up (CBU) tends to occur, which is accompanied by deterioration of image quality. This color separation (CBU) refers to disposing a plate having a striped window on the display surface of a liquid crystal display panel that displays, for example, striped R, G, and B colors in a field sequential manner, and placing the plate in the direction where the strip intersects the stripes. When the screen is viewed from the window side of the panel during directional vibration, a small-width color stripe remains as an afterimage visually. It stands to reason that the preferred display surface looks very white. For example, when black and white stripes are displayed field sequentially and the line of sight is moved rapidly, it refers to a phenomenon in which the ends of the black and white stripes appear reddish (色づく).

To improve this color separation (CBU), an improvement can be seen by adding a white (W) field to the three RGB fields (which may be referred to as three subfields) and setting one frame period to four fields as a whole. However, in order to set four fields within a frame, it is necessary to increase the field cycle of the LED drive circuit from triple to quadruple the frame cycle. Therefore, power consumption for driving increases.

Therefore, an object of the embodiments is to provide a display device and a method for driving the display device in which power consumption can be suppressed as a whole without greatly reducing the transmission efficiency.

Hereinafter, specific embodiments will be described. According to an embodiment, a display device includes a plurality of sub-pixels arranged along a first direction and a second direction crossing the first direction, a color filter corresponding to each sub-pixel, and an illumination device. The color filters include at least a blue filter adjacent to a yellow filter, and the lighting device has a light source having at least a period of cyan light output and a period of magenta light output in one frame period.

In addition, the disclosure is merely an example, and the contents that can be easily conceived by those skilled in the art to maintain the gist of the invention appropriately should be included in the scope of the present invention. In addition, in order to clarify the description, the drawings may schematically show the width, thickness, shape, etc. of each part in comparison with the actual form, but the interpretation does not limit the present invention. In addition, in this specification and each figure, the same reference numerals may be attached to components that perform the same or similar functions as those in the above-mentioned figures, and overlapping detailed descriptions may be omitted.

FIG. 1 is an exploded perspective view schematically showing a configuration example of a liquid crystal display device LCD in this embodiment. The liquid crystal display device LCD includes an active matrix liquid crystal display panel PNL, a double-sided tape TP, an optical sheet OS, a frame FR, a light guide plate LG, a light source unit LU, a reflection sheet RS, and an iron frame (ベゼル) BZ. The surface light source device LS is a lighting device that makes light incident on the liquid crystal display panel PNL. The surface light source device LS is configured to include at least a light guide plate LG and a light source unit LU.

The liquid crystal display panel PNL includes a flat first substrate SUB1 , a flat second substrate SUB2 disposed opposite to the first substrate SUB1 , and a liquid crystal layer held between the first substrate SUB1 and the second substrate SUB2 . In addition, since the liquid crystal layer is extremely thinner than the thickness of the liquid crystal display panel PNL, and is positioned inside the sealing material for bonding the first substrate SUB1 and the second substrate SUB2 , illustration thereof is omitted.

The liquid crystal display panel PNL includes a display area DA displaying an image at a region where the first substrate SUB1 and the second substrate SUB2 face each other. In the illustrated example, the display area DA is formed in a rectangular shape, and may also be called an effective display area. The liquid crystal display panel PNL is a transmissive liquid crystal display panel having a transmissive display function of displaying an image by selectively transmitting light from the surface light source device LS. The liquid crystal display panel PNL may have a display mode corresponding to a transverse electric field mode mainly using a transverse electric field substantially parallel to the principal surface of the substrate, or may have a structure corresponding to a longitudinal electric field mode mainly utilizing a longitudinal electric field substantially perpendicular to the principal surface of the substrate. The structure corresponding to the schema.

In the illustrated example, a driver IC chip CP and a flexible printed circuit board FPC are mounted on the first substrate SUB1 as signal supply sources for supplying signals necessary for driving the liquid crystal display panel PNL.

The optical sheet OS has light transmittance, and is located on the rear side of the liquid crystal display panel PNL, facing at least the display area DA. The optical sheet OS includes a diffusion sheet OSA, a prism sheet OSB, a prism sheet OSC, a diffusion sheet OSD, and the like. In the illustrated example, these optical sheets OS are all formed in a rectangular shape. In addition, the structure, such as the number and lamination|stacking of the diffusion sheet and the prism sheet included in the optical sheet OS, is an example, and is not limited to the example shown in FIG. 1 .

The frame FR is located between the liquid crystal display panel PNL and a bezel. In the illustrated example, the frame FR is formed in a rectangular frame shape and has a rectangular opening OP facing the display area DA. In addition, the shape of the frame FR is an example and is not limited to the example shown in FIG. 1 . In addition, when the frame FR is unnecessary, it does not need to be provided.

The double-sided tape TP is located between the liquid crystal display panel PNL and the frame FR outside the display area DA. This double-sided tape TP has light-shielding properties, for example, and is formed in a rectangular frame shape. Also, if the liquid crystal display panel PNL and the frame FR can be fixed without using the double-sided tape TP, the double-sided tape TP may not be provided.

The light guide plate LG is located between the frame FR and the iron frame BZ. The light guide plate LG is formed in a flat plate shape and has a first main surface LGA, a second main surface LGB opposite to the first main surface LGA, and a side face LGC connecting the first main surface LGA and the second main surface LGB.

The light source unit LU is arranged along the side face LGC of the light guide plate LG. The light source unit LU includes a plurality of light emitting diodes LED each functioning as a light source, a flexible circuit board LFPC on which a plurality of light emitting diodes LED is mounted, and the like. In the illustrated example, these light emitting diodes LED are arranged in a row along the side face LGC parallel to the short side of the light guide plate LG. In addition, the light-emitting diodes LED may be arranged along another side surface parallel to the long side of the light guide plate LG (a side surface intersecting the side surface LGC). That is to say, in FIG. 1 , the light emitting diodes LED are arranged along the first direction X, but they may also be arranged along the second direction Y intersecting it. As will be described in detail later, the light emitting diodes LED are driven in a field sequential manner.

The reflective sheet RS has light reflectivity and is located between the iron frame BZ and the light guide plate LG. In the illustrated example, the reflection sheet RS is formed in a rectangular shape.

The iron frame BZ accommodates the above-mentioned liquid crystal display panel PNL, double-sided tape TP, optical sheet OS, frame FR, light guide plate LG, light source unit LU, and reflection sheet RS. In the illustrated example, the surface light source device LS is arranged on the rear side of the liquid crystal display panel PNL, that is, on the side opposite to the first substrate SUB1, and functions as an illumination device (in this case, a so-called backlight).

FIG. 2 is a diagram schematically showing an example of a structure of a liquid crystal display panel PNL and an equivalent circuit. The display device includes an active matrix type liquid crystal display panel PNL. The liquid crystal display panel PNL includes a first substrate SUB1, a second substrate SUB2 disposed opposite to the first substrate SUB1, and a liquid crystal layer LQ held between the first substrate SUB1 and the second substrate SUB2. The display area DA corresponds to an area in which the liquid crystal layer LQ is held between the first substrate SUB1 and the second substrate SUB2, has a quadrangular shape, for example, and includes a plurality of sub-pixels arranged in a matrix. In this way, each sub-pixel is arranged in the vicinity of each intersection where the gate wiring in the first direction X intersects with the source wiring in the second direction Y, and the sub-pixel is selectively supplied to each of the plurality of sub-pixels. signal drive circuit.

In addition, in this specification, one sub-pixel refers to a pixel having a structure in which one pixel circuit and one color filter are integrated. Therefore, one sub-pixel has one color filter and expresses a single color. The smallest unit that can express a variety of colors in intermediate colors from primary colors by collecting a plurality of sub-pixels having different color filters is simply called a pixel or a composite pixel. As the combination of sub-pixels, as will be described later, a combination of sub-pixels with red, green, and blue color filters, a combination of sub-pixels with yellow and blue color filters, a combination of sub-pixels with yellow, blue, and white The combination of sub-pixels of the color filter, etc.

The first substrate SUB1 has a plurality of gate wirings G (G1-Gn) extending along the first direction X (also referred to as the row direction or lateral direction) on the display area DA, and a plurality of gate wirings G (G1-Gn) extending along the first direction X A plurality of source wirings S ( S1 to Sm ) extending in a direction Y (may also be referred to as a column direction or a vertical direction).

In addition, as one representative example is shown on the right side of FIG. Among the sub-pixels, the pixel electrode PE electrically connected to the switching element SW, the common electrode CE1 facing the pixel electrode PE, and the like. Although two common electrodes CE1 are shown, they are actually integrated electrodes. The storage capacitor CS is, for example, formed between the common electrode CE1 and the pixel electrode PE. The second substrate SUB2 faces the first substrate SUB1 with the liquid crystal layer LQ interposed therebetween. In addition, the storage capacitor CS may or may not be provided as required. For example, when the liquid crystal display device LCD is in the FFS (FringeFieldSwitching, fringe field switching) mode, since the pixel electrode PE, the common electrode CE1 and the insulator disposed between them function as the storage capacitor CS, it is not necessary to separately Set storage capacitor CS.

Each gate wiring G (G1-Gn) is drawn out to the outside of the display area DA, and is connected to the first drive circuit GD. Each source wiring S (S1-Sm) is drawn out to the outside of the display area DA, and is connected to the second drive circuit SD. The first drive circuit GD and the second drive circuit SD are, for example, at least partly formed on the first substrate SUB1 and connected to a drive IC chip (also sometimes referred to as a liquid crystal driver or a drive circuit control unit) CP.

In order to implement the column inversion driving method, the second drive circuit SD can output pixel signals of different polarities when outputting pixel signals to source wirings of adjacent columns. The drive IC chip CP incorporates a controller for controlling the first drive circuit GD and the second drive circuit SD, and functions as a signal supply source for supplying signals necessary for driving the liquid crystal display panel PNL. In the illustrated example, the driver IC chip CP is mounted on the first substrate SUB1 outside the display area DA of the liquid crystal display panel PNL.

The common electrode CE1 extends over the entire display area DA, and is formed commonly for a plurality of sub-pixels. The common electrode CE1 is drawn out to the outside of the display area DA, and is connected to the power supply unit Vcom. The power supply unit Vcom is formed on the first substrate SUB1 outside the display area DA, for example, and is electrically connected to the common electrode CE1. A constant common voltage is supplied to the power supply unit Vcom.

The color filters are arranged on a plurality of sub-pixels with prescribed rules. The color filters face the pixel electrodes with the liquid crystal layer LQ interposed therebetween, and are formed on the second substrate SUB2.

The above-mentioned plurality of sub-pixels form, for example, the first column, the second column, the third column, ..., the color filter of the first column is blue (B), and the color filter of the second column is yellow (Y). The color repeats continuously toward the first direction X. Furthermore, when comparing the width H1 of the blue filter and the width H2 of the yellow filter, the width of the yellow filter is formed larger than that of the blue filter.

FIG. 3A shows an example of arrangement of color filters of each sub-pixel and an example of colors of the lighting device. In FIG. 3A , in order to make the arrangement of the color filters easier to understand, structures such as the source wiring S ( S1 to Sm ) on the first substrate SUB1 side are omitted and shown.

In the first direction X (horizontal direction of the figure), the blue filter (width H1) and the yellow filter (width H2) are repeatedly arranged. Color filters are formed on the second substrate SUB2. In this display device, its surface light source device, that is, an illumination device, is driven in a field sequential manner. Here, the plurality of light-emitting diodes LEDs of the lighting device include light-emitting diodes that emit light in cyan and magenta. The plurality of light emitting diodes LEDs are mounted on a flexible circuit substrate LFPC.

A cyan light emitting diode can be realized by, for example, laminating a green phosphor on a blue light emitting diode. A magenta light-emitting diode can be realized by, for example, laminating a red phosphor on a blue light-emitting diode. The cyan light-emitting diode is turned on (lighted) during, for example, the first half period of one frame, and turned off (lit off) during the second half period of one frame. One magenta light-emitting diode is driven so that it is turned off (turned off) during the first 1/2 period of one frame, and turned on (lit) during the second half period of one frame.

The light emitting diodes LED are arranged in a row parallel to the short sides of the light guide plate. The light emitted from the light emitting diode LED is incident on the light guide plate. As a result, surface emission (light in which cyan and magenta are periodically repeated) emitted from the light guide plate is transmitted through the pixels in the light-transmitting state. Here, since the driving method is the field sequential method, surface emission becomes light in which cyan and magenta are periodically repeated.

FIG. 3B shows the relationship between the fields of cyan and magenta, which are the emission colors of the lighting device, and the color of light emitted from the color filter. The lighting device has a cyan field (1/2 frame) and a magenta field (1/2 frame) during one frame. The colors that can be displayed on the display surface of the display device in the cyan field (1/2 frame) are blue (B) and green (G). In contrast, the colors that can be displayed on the display surface of the display device in the magenta field (1/2 frame) are blue (B) and red (R).

As can be seen from FIG. 3B, blue (B) can be displayed regardless of whether it is a cyan field or a magenta field. On the contrary, green (G) can be displayed only in the cyan field, and red (R) can be displayed only in the magenta field. As a result, the output level (luminescence intensity) of blue (B) tends to be stronger than that of green (G) and red (R).

In order to solve this imbalance, in this device, for example, as shown in FIG. 3A and FIG. 3C , the emission intensity of blue (B), green (G), and red (R) emission colors is balanced.

That is, the width H1 of the blue filter is made smaller than the width H2 of the yellow filter so that the area of the blue filter becomes smaller than the area of the yellow filter. Thereby, as shown in FIG. 3C , it is contrived that the luminous intensity of blue (B), green (G), and red (R) become almost equal during one frame.

Also, in order to obtain white balance, the luminous intensity of blue (B), green (G), and red (R) are not necessarily equal. In order to obtain the position of white on the chromaticity diagram, it is preferable to set the emission intensities of blue (B), green (G), and red (R) in consideration of the characteristics (transmittance, etc.) of each color filter.

In the above-mentioned embodiments, although one frame includes two fields, the cyan field and the magenta field, the present invention is not limited thereto.

In FIG. 4A , FIG. 4B and FIG. 4C , one frame includes three fields of cyan field, magenta field and white field. Therefore, as shown in FIG. 4A , the plurality of light-emitting diodes (LEDs) constituting the lighting device include light-emitting diodes whose light-emitting colors are cyan, white, and magenta.

In addition, the light source unit LU having a plurality of light emitting diodes LED shown in FIG. 3A and FIG. 4A is arranged on the end face side in the first direction X of the light guide plate. However, the arrangement position of the light source unit LU is not limited. The light source unit LU may also be disposed on the end surface of the light guide plate in the second direction Y. The light source unit LU shown in FIG. 4A is capable of providing a cyan field, a white field, and a magenta field. In FIG. 4A , although white light emitting diodes are shown, the light source unit LU does not necessarily have to have white light emitting diodes. This is because, as shown in FIGS. 9A and 9B described later, a white field can be provided by simultaneously lighting cyan and magenta light-emitting diodes.

FIG. 4B shows timing when one frame period is divided into a cyan field, a white field, and a magenta field. Furthermore, the relationship between the fields of cyan, white, and magenta, which are the light emission colors of the lighting device, and the color of light emitted from the color filter is shown. The lighting device has a cyan field (1/3 frame), a white field (1/3 frame), and a magenta field (1/3 frame) during one frame. The colors that can be displayed on the display surface of the display device in the cyan field (1/3 frame) are blue (B) and green (G). The colors that can be displayed on the display surface of the display device in the white field (1/3 frame) are blue (B), green (G) and red (R), and in this case, white (W) can be displayed as a result. The colors that can be displayed on the display surface of the display device in the magenta field (1/3 frame) are blue (B) and red (R).

FIG. 4C shows a situation in which white (W=R, G, B) light-emitting diodes are added on the basis of the cyan field and the magenta field during one frame period shown in FIG. 3C . In this embodiment, since one frame is divided into three fields, the switching frequency of the lighting device is increased compared to the case where one frame is divided into two fields in the previous embodiment. However, in the case of a conventional device having a W field, there are four fields of R, G, B, and W fields, and the present embodiment has one field less than the conventional device. Therefore, even if the W field is increased, the power consumption of the present embodiment does not increase like that of conventional devices.

FIG. 5 shows the transmittance of the blue filter and the yellow filter according to the wavelength. In addition, characteristic curves of the light emission energy of a blue (B) LED, a green (G) phosphor, and a red (R) phosphor as a function of wavelength are shown. The characteristic curve showing the transmittance of the blue filter almost coincides with the characteristic curve of the light emission energy of the blue (B) LED. The emission energy of the green (G) phosphor transmits green light in the vicinity of 540nm to 550nm through the yellow filter. The emission energy of the red (R) phosphor transmits the red light in the vicinity of 630nm to 650nm through the yellow filter.

6 is a comparison of the aperture ratio and transmittance of a pixel with a yellow filter and a sub-pixel with a blue filter, and a sub-pixel without a filter in one embodiment. And shown in the figure. The sub-pixel without a filter has an aperture ratio of 78.8% and a transmittance of 25.3%. In contrast, the aperture ratio of the sub-pixel with the yellow filter in the embodiment is 67.0%, and the transmittance is 13.0%, and the aperture ratio of the sub-pixel with the blue filter is 57.8%, and the transmittance is 0.34%. %.

FIG. 7A shows elements referred to in order to obtain the LED effect. In FIG. 7A , each luminance (1.7 candela) and current (30 mA) of a red (R) LED, a green (G) LED, and a blue (B) LED are shown. This value means that the LED requires a current of 30mA in order to obtain 1.7 candela of light. The LED effect is obtained from this value. That is, the LED effect is the brightness level relative to the current. For example, {(1.7)/30}=0.056 is obtained. And, this LED effect 0.056 is defined as 100.

On the other hand, FIG. 7A shows the luminance (2.7 candela) and current (20mA) of phosphor LEDs (elements configured to output cyan or magenta light by laminating phosphors on LEDs of a predetermined color and configured to output light in cyan or magenta). . This value means that the phosphor LED requires 20mA of current to obtain 2.7 candela. From this value, the LED effect {(2.7)/20}=0.135 can be obtained. Then, obtain the relative value 251 with the previous LED effect 0.056=100.

In addition, cyan light emission can be obtained by combining a green (G) light-emitting phosphor with an LED that emits blue (B) light. In addition, magenta light emission can be obtained by combining a red (R) light-emitting phosphor with an LED that emits blue (B) light.

In FIG. 7A, values including duty cycle loss are also shown. The so-called loss of duty ratio is a value derived from the experimental results that the LED effect drops by about 10% when driving by field sequence.

Thus, LED effect 100 becomes LED effect 90 when duty cycle loss is considered, and LED effect 251 becomes LED effect 226 when duty cycle loss is considered.

7B is a graph comparing the aperture ratio, transmittance, and LED effect of the embodiment of the present application with those of the conventional field sequential method. The aperture ratio of the RGB field sequential method realized by the time-sharing light emission of the R LED, the G LED, and the B LED without a filter is 78.8%, the transmittance is 25.3%, and the LED effect is 90%.

On the other hand, in the first field-sequential method realized by the blue filter and the yellow filter, and the emission color of the backlight is cyan and magenta, the aperture ratio (B=57.8%, Y=67.8%), The transmittance is 13.3%, and the LED effect is 226 (however, the area ratio of the B filter and the Y filter is 1:2). Or, in the second field sequential method realized by blue and yellow filters, and the luminous colors of the lighting device being cyan and magenta, aperture ratio (B=49.9%, Y=73.0%), transmittance The pass rate is 16.1%, and the LED effect is 226 (however, it is the case that the area ratio of the B filter and the Y filter is 1:3).

Here, if the transmittance a and the LED effect b are multiplied as the power efficiency of the lighting device, then

The above-mentioned RGB field sequential method becomes ... 22.8,

The first field-sequential approach above becomes ... 30.1,

The above-mentioned second field sequential mode becomes ... 36.4.

From this, it can be seen that the lighting device according to the embodiment of the present application has excellent power efficiency.

FIG. 8A shows the distance of color change on the chromaticity diagram in the case where the display color changes over a region including primary colors R, G, and B with arrows. In addition, FIG. 8B shows the distance of color change on the chromaticity diagram when the display color changes in the region of cyan and magenta with arrows. As is known from comparing the two, the distance in the case of displaying a color change over an area of cyan and magenta is shorter than the distance in the case of displaying a color change over an area including primary colors R, G, and B. This means that the difference in chromaticity is small when the display color is changed. Thereby, color break-up (CBU) is reduced.

9A is a timing chart showing another embodiment and an operation when the lighting device has a white (W) light emitting field in addition to a cyan light emitting field and a magenta light emitting field. In order to obtain a white (W) light emitting field, a cyan phosphor LED and a magenta phosphor LED are simultaneously turned on. Therefore, white (W) light emitting diodes as shown in FIG. 4A are not required. This lighting control is not shown, but is performed by a lighting device control circuit (may also be referred to as a backlight control circuit) in the driver IC chip CP (shown in FIG. 2 ) for driving the LCD.

As a result, in the cyan luminous field, intermediate color representations of green and blue, and green and blue can be performed, and in the magenta luminous field, intermediate color representations of red and blue, and red and blue can be performed. Under a white (W) luminous field, red, green, and blue (that is, white (W)) color representations can be performed.

Figure 9B is yet another embodiment. In the embodiment shown in FIG. 9A , a yellow filter and a blue filter are used as color filters. However, in the embodiment shown in FIG. 9B , yellow filters, blue filters, and white (W) filters are used as color filters. The lighting sequence of the lighting devices is the same as in the case of FIG. 9A . That is, the lighting device has a white (W) light emitting field in addition to a cyan light emitting field and a magenta light emitting field.

In the cyan light emission field, blue, green, and their intermediate colors can be represented, and in the magenta light emission field, blue, red, and their intermediate colors can be represented. Moreover, in a white (W) luminous field, color representation of red, green, and blue (that is, white (W)) can be performed.

FIG. 10A is a diagram showing an embodiment in a case where a filter includes white (W), yellow (Y), and blue (B). In this embodiment, the areas of the white (W), yellow (Y), and blue (B) filters are formed to be equal. The white (W), yellow (Y), and blue (B) filters correspond to sub-pixels, respectively. The whole of the white (W), yellow (Y), and blue (B) filters and the respective sub-pixels can be referred to as one pixel (or unit pixel). Through this pixel, any color in RGB can be represented, and the sub-pixel is used to form a pixel. The shape of the pixels (white (W), yellow (Y), blue (B) synthesis filters) is, for example, a square when viewed from above.

FIG. 10B is a diagram illustrating an example of a pixel circuit corresponding to the filter of FIG. 10A . The configuration of each pixel circuit forming each sub-pixel has been explained in FIG. 2 . That is, each pixel circuit of each sub-pixel has a switching element, and the switching element is composed of, for example, a thin film transistor (TFT), the gate is connected to the gate line G, the source is connected to the signal line S, and the drain is connected to the liquid crystal for driving the liquid crystal layer. The pixel electrode connection.

FIG. 11A is a diagram illustrating another embodiment in which the filter includes white (W), yellow (Y), and blue (B). In this embodiment, the respective areas of the yellow (Y) filter and the white (W) filter are formed larger than the area of the blue (B) filter.

FIG. 11B is a diagram illustrating an example of a pixel circuit corresponding to the filter of FIG. 11A . The configuration of each pixel circuit forming each sub-pixel has been explained in FIG. 2 . When viewed along the column direction (second direction Y), blue (B) sub-pixels are arranged continuously. However, yellow (Y) sub-pixels and white (W) sub-pixels are alternately arranged when viewed along the column direction (second direction Y). In addition, yellow (Y) sub-pixels and white (W) sub-pixels are alternately arranged when viewed along the row direction (first direction X). In this embodiment, the planar shape of a pixel (unit pixel) is also a square. In addition, in the configuration of FIG. 11B , one blue (B) filter is assigned to each of one yellow (Y) filter and one white (W) filter. That is, in the structure of FIG. 11B, one blue (B) filter is arranged in one pixel.

FIG. 11C is a diagram illustrating another example of a pixel circuit corresponding to the filter of FIG. 11A . The pixel circuit shown in FIG. 11B is different from the pixel circuit shown in FIG. 11C in that blue (B) sub-pixels are formed across two rows. That is, the source and the gate of the switching element of the blue (B) sub-pixel are respectively connected to the gate wiring G1 and the source wiring S1, including the pixel electrode of the sub-pixel and the blue (B) filter It is formed extending from the first row to the second row together with the switching elements. Thus, a blue (B) filter is shared with a yellow (Y) filter and a white (W) filter. That is, in the structure of FIG. 11C, one blue (B) filter is arranged across a plurality of pixels.

FIG. 12A is a diagram showing yet another embodiment in which the filter includes white (W), yellow (Y), and blue (B). In this embodiment, yellow (Y) sub-pixels and white (W) sub-pixels are repeatedly arranged in the row direction (first direction X) of the first row, and arranged in the row direction (first direction X) of the second row. For blue (B) sub-pixels, one blue (B) sub-pixel has the length of two white (W) and yellow (Y) sub-pixels. For example, in FIG. 12B showing an example of a pixel circuit corresponding to the filter of FIG. 12A , the source and gate of the switching element of the blue (B) sub-pixel are connected to the gate wiring G2 and the source wiring S2, respectively. The connection, including the pixel electrode of the sub-pixel and the blue (B) filter is formed by extending from the first column to the second column together with the switching element. In this embodiment, the planar shape of a pixel (unit pixel) is also a square.

FIG. 12C is a diagram illustrating another example of a pixel circuit corresponding to the filter of FIG. 12A . Differences between the pixel circuit shown in FIG. 12B and the pixel circuit shown in FIG. 12C will be described. The blue (B) sub-pixels of FIG. 12B are formed across two columns, whereas the blue (B) sub-pixels shown in FIG. 12C are formed on each column.

13 is a graph showing an example of a curve of spectral transmittance of a blue (B) filter and a yellow (Y) filter. A blue (B) filter easily transmits light having a wavelength near 450 nm (this transmittance is, for example, Tb). A yellow (Y) filter easily transmits light having a wavelength near 580 nm (this transmittance is, for example, Ty).

FIG. 14 is an explanatory diagram showing a calculation example of the area ratio of a blue (B) filter and a yellow (Y) filter to a pixel. For example, the width of the yellow (Y) filter is a, and the width of the blue (B) filter is b, and it is assumed that the lengths of the two filters are the same. Therefore, it can be expressed as

Area ratio of blue (B) filter = b/(a+b)

The area ratio of the yellow (Y) filter=a/(a+b).

As mentioned above, since the spectral transmittance Tb and Ty of the blue (B) filter and the yellow (Y) filter are known, the spectral transmittance Tb, Ty and blue The transmittance ratio of the color filter is obtained by the area ratio (b/(a+b)) and (a/(a+b)) of the color (B) filter and the yellow (Y) filter.

The transmittance ratio of the color filter can be expressed, for example, as (Tb×b/(a+b))/(Ty×a/(a+b))

FIG. 15 is a graph showing a characteristic example of spectral luminance when a magenta LED and a cyan LED of the lighting device are simultaneously made to emit light. The characteristic of spectral luminance shows that the energy of light having wavelengths around 450 nm and around 580 nm is high. However, the energy of light with a wavelength around 450 nm is stronger than the energy of light with a wavelength around 580 nm. From this characteristic, the luminance ratio of magenta and cyan can be obtained. The so-called luminance ratio of the lighting device can be obtained, for example, as (luminance at 450 nm/luminance at 580 nm).

FIG. 16 shows the transmittance ratio (Tb×b/(a+b))/( A graph of the relationship between Ty×a/(a+b)) and the luminance ratio (450nm luminance/580nm luminance) of the lighting device.

In addition, in FIG. 16 , the transmittance ratio of the color filter is shown on the horizontal axis, and the luminance ratio of the lighting device is shown on the vertical axis.

Here, the lighting device luminance ratio is a ratio of (luminance at 450 nm/luminance at 580 nm) calculated from the spectral luminance characteristics (shown in FIG. 15 ) when the magenta and cyan colors of the lighting device are simultaneously turned on.

Δy=-0.02 or less

Δy=-0.02～0.00

Δy=0.00～0.02

Δy=0.02～0.04

Δy=0.04～0.06

Δy=0.06 or more

is shown by the graph. A characteristic line of an offset Δy=0.00 from the chromaticity point of white is shown by a thick broken line. When the amount of shift Δy is 0.00 or less, white which is a chromaticity reference can be obtained satisfactorily.

Therefore, at the design stage, as long as either the luminance ratio of the lighting device or the transmittance ratio of the color filter is determined, the other transmittance ratio or luminance ratio can be determined using the characteristics of the graph.

As described above, the correlation between the filter transmittance ratio obtained from the area ratio of the blue filter and the yellow filter and the spectral luminance ratio of magenta and cyan light includes maintaining A characteristic of the point where the white point is located on the chromaticity diagram. Therefore, the above-mentioned correlation can be set so as to maintain the characteristics of the white point position on the chromaticity diagram.

An expression representing the characteristic line of the above-mentioned graph is, for example,

265－0.419×(transmittance ratio of color filter)

−0.041×brightness ratio of the lighting device=Δy. When the shift amount Δy is 0.00 or less, it can be expressed as Δy≦0.

According to the above-described embodiments, it is possible to provide a display device and a display method in which power consumption can be suppressed as a whole without greatly reducing the transmission efficiency.

That is, according to the device of the embodiment, since the device has a color filter, the power efficiency (LED effect) of the lighting device is higher than that of a field sequential device without a filter, and therefore the overall power efficiency is excellent.

One aspect of the disclosed invention is as follows:

(1) A display device having: a plurality of sub-pixels arranged along a first direction and a second direction intersecting with the first direction, a color filter corresponding to each sub-pixel, and an illuminating device,

The color filters include at least adjacent blue filters and yellow filters,

The lighting device has a light source, and one frame period of light output from the light source has at least a cyan light output period and a magenta light output period.

(2) The display device according to (1), further including a sub-pixel having a white color filter.

(3) The display device according to (1), wherein the light source further has a period for outputting white light within the one frame period.

(4) The display device according to (1), wherein the one frame period of the light output from the light source further has a period in which white light is output, and the period in which white light is output is equal to that of the cyan color. During the period when light and magenta light are turned on at the same time.

(5) The display device according to (1), wherein the blue filter has a smaller area than the yellow filter.

(6) The display device according to (1), comprising pixels having the blue filter and the yellow filter and having a substantially square planar shape, or pixels having the blue filter The light sheet, the yellow filter and the white filter are substantially square pixels in plane shape.

(7) The display device according to (1), wherein the blue color filters are arranged in the first direction, and the yellow color filters and the color filters are arranged alternately in the first direction. White filter.

(8) The display device according to (1), wherein the blue color filters are arranged in the second direction, and the yellow color filters and the color filters are arranged alternately in the second direction. White filter.

(9) The display device according to (7), wherein one blue filter is assigned to one yellow filter and one white filter, respectively.

(10) The display device according to (8), wherein one blue filter is assigned to one yellow filter and one white filter, respectively.

(11) The display device according to (7), wherein one blue filter is shared by one yellow filter and one white filter.

(12) The display device according to (8), wherein one blue filter is shared by one yellow filter and one white filter.

(13) The display device according to (1), wherein the light source is controlled based on a backlight control circuit.

(14) The display device according to (1), wherein the filter transmittance ratio obtained from the area ratio of the blue filter to the yellow filter and the spectra of the magenta and cyan light The correlation between the luminance ratios is a characteristic that maintains the position of the white point on the chromaticity diagram.

(15) A method for driving a display device, wherein the display device has: a plurality of sub-pixels arranged in a first direction and a second direction intersecting the first direction, a color filter corresponding to each sub-pixel, and lighting fixtures,

The color filters include at least adjacent blue filters and yellow filters,

The lighting device outputs at least cyan light and magenta light in one frame period.

(16) The method for driving a display device according to (15), wherein the lighting device outputs white light in the one frame period.

(17) The method for driving a display device according to (15), wherein the illuminating device outputs white light in the one frame period, and simultaneously turns on the cyan light in a field in which the white light is output. light and magenta light.

While certain embodiments of the inventions have been described, these embodiments have been presented by way of illustration only, and are not intended to limit the scope of the inventions. Indeed, the various novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The appended claims and their equivalents are intended to cover such forms or modifications as fall within the scope and spirit of the invention.

Claims (15)

1. a display unit, it is characterised in that, have:

Multiple sub-pixel, along first party to and with described first party to intersect second direction arrangement;

Colour filter is corresponding with each sub-pixel; And

Means of illumination,

Described colour filter at least comprises adjacent blue color filter and yellow filter,

Described means of illumination has light source, during the light output at least having a cyan during a frame of the light exported from light source and during the light output of magenta.

2. display unit according to claim 1, it is characterised in that, described display unit also comprises the sub-pixel of the spectral filter with white.

3. display unit according to claim 1, it is characterised in that, described light source during a described frame in also have export white light during.

4. display unit according to claim 1, it is characterized in that, during also there is the light exporting white during a described frame of the light exported from described light source, it is during the light of described cyan and the light of magenta are lighted simultaneously during exporting the light of described white.

5. display unit according to claim 1, it is characterised in that, described in the area ratio of the spectral filter of described blueness, the area of the spectral filter of yellow is little.

6. display unit according to claim 1, it is characterized in that, described display unit comprises the spectral filter of the spectral filter with described blueness and described yellow and planeform is the pixel of square or has the spectral filter of described blueness, the spectral filter of described yellow and a spectral filter of white and planeform is the pixel of square.

7. display unit according to claim 1, it is characterised in that, it is arranged with the spectral filter of described blueness in said first direction, it is arranged with the spectral filter of described yellow and the spectral filter of white in said first direction alternately.

8. display unit according to claim 1, it is characterised in that, it is arranged with the spectral filter of described blueness in this second direction, it is arranged with the spectral filter of described yellow and the spectral filter of white in this second direction alternately.

9. display unit according to claim 7 or 8, it is characterised in that, distribute a blue spectral filter respectively to the spectral filter of a yellow and a white spectral filter.

10. display unit according to claim 7 or 8, it is characterised in that, a blue spectral filter is common by the spectral filter of a yellow and a white spectral filter.

11. display unit according to claim 1, it is characterised in that, described light source is controlled based on backlight control circuit.

12. display unit according to claim 1, it is characterized in that, the mutual relationship between the spectral filter transmitance ratio obtained by the area ratio of the spectral filter of described blueness and the spectral filter of described yellow and the spectral brightness ratio of the light of magenta and cyan is the characteristic of the white point position maintaining on chromaticity diagram.

The driving method of 13. 1 kinds of display unit, it is characterised in that,

Described display unit has: along first party to and with described first party to multiple sub-pixel colour filter corresponding with each sub-pixel of the second direction arrangement intersected and means of illumination,

Described colour filter at least comprises adjacent blue color filter and yellow filter,

Described means of illumination during a frame at least export the light of cyan and the light of magenta.

The driving method of 14. display unit according to claim 13, it is characterised in that, described means of illumination during a described frame in export white light.

The driving method of 15. display unit according to claim 13, it is characterised in that, described means of illumination during a described frame in export white light, export white light field in, light the light of described cyan and the light of described magenta simultaneously.