Display device comprising grayscale conversion portion and display portion

Patent metadata

Field	Value
Publication number	US-9711110-B2
Application number	US-201313833870-A
Country	US
Kind code	B2
Filing date	Mar 15, 2013
Priority date	Apr 6, 2012
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

A dark portion in an image seen by a viewer is expressed more precisely, whereby the image given a greater sense of depth is displayed. A display device in which pixels each include a light-emitting module capable of emitting light having a spectral line half-width of less than or equal to 60 nm in a response time of less than or equal to 100 μs and are provided at a resolution of higher than or equal to 80 ppi; the NTSC ratio is higher than or equal to 80%; and the contrast ratio is higher than or equal to 500, is provided with a circuit converting an image signal having a given grayscale into an image signal capable of representing an image on the low luminance side by high-level grayscale.

First claim

What is claimed is:

1. A display device comprising:
a grayscale conversion portion; and
a display portion including a plurality of pixels provided at a resolution of 80 ppi or more, one of the plurality of pixels comprising a light-emitting module capable of emitting light with a spectral line having a peak in which a half width of the peak is 60 nm or less and a transistor including an oxide semiconductor,
wherein the light-emitting module includes an organic EL element and a color filter,
wherein the grayscale conversion portion is configured to convert a first image signal inputted to the grayscale conversion portion into a second image signal and transmit the second image signal to the display portion,
wherein the first image signal has p gray levels (p is a natural number and an even number),
wherein the second image signal is subjected to a grayscale conversion processing in which each of q gray levels from the lowest gray level to the q-th gray level is further divided into 2 r gray levels, and
wherein q is greater than or equal to 1 and less than or equal to p/2 and r is greater than or equal to 1 and less than or equal to 20.

2. The display device according to claim 1 ,
wherein the grayscale conversion portion is configured to divide an image contained in the first image signal into a plurality of regions, extract luminance distribution in each of the plurality of regions, determine whether to perform the grayscale conversion processing in each of the plurality of regions based on the luminance distribution, and perform the grayscale conversion processing to a region which needs the grayscale conversion processing.

3. The display device according to claim 1 ,
wherein the organic EL element is one of a first organic EL element, a second organic EL element, and a third organic EL element,
wherein the first organic EL element comprises:
a first reflective film;
a first light-emitting layer over the first reflective film;
an interlayer over the first light-emitting layer;
a second light-emitting layer over the interlayer; and
a semi-transmissive and semi-reflective film over the second light-emitting layer,
wherein a first optical path length between the first reflective film and the semi-transmissive and semi-reflective film is adjusted to i/2 times (i is a natural number) the length greater than or equal to 600 nm and less than 800 nm,

wherein a first color filter for transmitting light exhibiting red color is provided over the first organic EL element,
wherein the second organic EL element comprises:
a second reflective film;
the first light-emitting layer over the second reflective film;
the interlayer over the first light-emitting layer;
the second light-emitting layer over the interlayer; and
the semi-transmissive and semi-reflective film over the second light-emitting layer,
wherein a second optical path length between the second reflective film and the semi-transmissive and semi-reflective film is adjusted to j/2 times (j is a natural number) the length greater than or equal to 500 nm and less than 600 nm, and

wherein a second color filter for transmitting light exhibiting green color is provided over the second organic EL element,
wherein the third organic EL element comprises:
a third reflective film;
the first light-emitting layer over the third reflective film;
the interlayer over the first light-emitting layer;
the second light-emitting layer over the interlayer; and
the semi-transmissive and semi-reflective film over the second light-emitting layer,
wherein a third optical length between the third reflective film and the semi-transmissive and semi-reflective film is adjusted to k/2 times (k is a natural number) the length greater than or equal to 400 nm and less than 500 nm, and

wherein a third color filter for transmitting light exhibiting blue color is provided over the third organic EL element.

4. The display device according to claim 1 ,
wherein the organic EL element is one of a first organic EL element, a second organic EL element, and a third organic EL element,
wherein the first organic EL element comprises:
a first reflective film;
a first electrode over the first reflective film;
a first light-emitting layer over the first electrode;
an interlayer over the first light-emitting layer;
a second light-emitting layer over the interlayer; and
a semi-transmissive and semi-reflective film over the second light-emitting layer,

wherein a first color filter for transmitting light exhibiting red color is provided over the first organic EL element,
wherein the second organic EL element comprises:
a second reflective film;
a second electrode over the second reflective film;
the first light-emitting layer over the second electrode;
the interlayer over the first light-emitting layer;
the second light-emitting layer over the interlayer; and
the semi-transmissive and semi-reflective film over the second light-emitting layer,

wherein a second color filter for transmitting light exhibiting green color is provided over the second organic EL element,
wherein the third organic EL element comprises:
a third reflective film;
a third electrode over the third reflective film;
the first light-emitting layer over the third electrode;
the interlayer over the first light-emitting layer;
the second light-emitting layer over the interlayer; and
the semi-transmissive and semi-reflective film over the second light-emitting layer,

wherein a third color filter for transmitting light exhibiting blue color is provided over the third organic EL element.

5. The display device according to claim 1 ,
wherein the organic EL element comprises:
a reflective film;
a first light-emitting layer over the reflective film;
an interlayer over the first light-emitting layer;
a second light-emitting layer over the interlayer; and
a semi-transmissive and semi-reflective film over the second light-emitting layer,
wherein the light-emitting module is configured to emit light that exhibits red and the half width of the peak is less than 50 nm,

wherein the color filter is for transmitting light exhibiting red color and provided over the organic EL element.

6. An electronic device comprising the display device according to claim 1 .

7. The display device according to claim 1 ,
wherein the oxide semiconductor include c-axis aligned crystal.

8. The display device according to claim 1 ,
wherein a region where a channel of the transistor is formed in the oxide semiconductor is a single crystal semiconductor.

9. The display device according to claim 1 ,
wherein the resolution is 300 ppi or higher.

10. The display device according to claim 1 ,
wherein the display portion has a contrast ratio of 2000 or higher.

11. A display device comprising:
a display portion comprising a plurality of pixels;
one of the plurality of pixels comprising:
a light-emitting module including an organic EL element and a color filter, the light-emitting module capable of emitting light with a spectral line having a peak in which a half width of the peak is 60 nm or less; and
transistor including an oxide semiconductor, and

a grayscale conversion portion,
wherein the display portion has an NTSC ratio of 80% or higher and a contrast ratio of 500 or higher,
wherein the plurality of pixels are provided at a resolution of 80 ppi or more,
wherein the grayscale conversion portion is configured to convert a first image signal inputted to the grayscale conversion portion into a second image signal and transmit the second image signal to the display portion,
wherein the first image signal has p gray levels (p is a natural numbe

Assignees

• Semiconductor Energy Lab

Inventors

• Yamazaki Shunpei
• Hirakata Yoshiharu

Classifications

• G09G2320/0271

  Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping · CPC title

• H01L27/322

  Electricity · mapped topic

• G09G3/3208

  organic, e.g. using organic light-emitting diodes [OLED] · CPC title

• H04N13/0033

  Electricity · mapped topic

• H01L51/5278

  Electricity · mapped topic