# US 10,504,477 B2 · Display device

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- Number: US 10,504,477 B2
- Document ID: US10504477B2
- Status: Granted
- Kind: B2
- Application number: 15/872,388
- Filed: 2018-01-16
- Published: 2018-07-26
- Granted: 2019-12-10
- Earliest claimed: 2017-01-23
- Assignees: Japan Display Inc.
- Applicants: Japan Display Inc.
- Inventors: Hirofumi Kato
- Web page: https://patentgrep.com/patent/US10504477B2

## CPC

- G09G 3/3696: {Generation of voltages supplied to electrode drivers}
- G02F 1/1334: based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
- G02F 1/133621: {providing coloured light (G02F1/133617, G02F1/133533 take precedence)}
- G02F 1/134309: {characterised by their geometrical arrangement}
- G02F 1/1345: Conductors connecting electrodes to cell terminals
- G02F 1/137: characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
- G09G 3/2092: {Details of a display terminals using a flat panel, the details relating to the control arrangement of the display terminal and to the interfaces thereto (suitable for both CRT and flat panel G09G5/003; specific for a CRT G09G1/165)}
- G09G 3/3413: {Details of control of colour illumination sources}
- G09G 3/3607: {for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels (display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127)}
- G09G 3/3611: {Control of matrices with row and column drivers}
- G09G 3/3614: {Control of polarity reversal in general}
- G09G 3/3648: {using an active matrix (G09G3/367 - G09G3/3696 take precedence)}
- G09G 3/3655: {Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors}
- G09G 3/3674: {Details of drivers for scan electrodes}
- G02F 1/133342: {for double-sided displays}
- G02F 1/13347: {working in reverse mode, i.e. clear in the off-state and scattering in the on-state}
- G02F 1/133616: {Front illuminating devices}
- G02F 1/133622: {Colour sequential illumination}
- G02F 2201/121: common or background
- G02F 2201/123: pixel
- G09G 2300/0456: with a reflective area and a transmissive area combined in one pixel, such as in transflectance pixels
- G09G 2300/0478: related to liquid crystal pixels
- G09G 2300/0495: Use of transitions between isotropic and anisotropic phases in liquid crystals, by voltage controlled deformation of the liquid crystal molecules, as opposed to merely changing the orientation of the molecules as in, e.g. twisted-nematic [TN], vertical-aligned [VA], cholesteric, in-plane, or bi-refringent liquid crystals
- G09G 2310/0237: Switching ON and OFF the backlight within one frame
- G09G 2310/08: Details of timing specific for flat panels, other than clock recovery
- G09G 2320/062: Adjustment of illumination source parameters
- G09G 2320/064: by time modulation of the brightness of the illumination source
- G09G 2320/0666: for control of colour parameters, e.g. colour temperature
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS

## Abstract

According to one embodiment, a display device includes a display panel including a plurality of pixel electrodes, a common electrode and a display function layer, a light source unit, and a controller. When a character is displayed in a first area of a display area, the controller applies a color other than the achromatic color to the first area, and makes a second area and a non-object area transparent. Transparency of the non-object area is higher than transparency of the second area.

## Claims

### Claim 1

A display device comprising:
a display panel comprising:
a plurality of pixel electrodes located in a display area, and provided in each of a plurality of rows;
a common electrode located in the display area; and
a display function layer located in the display area;
a light source unit located a non-display area outside the display area, and emitting light in a color other than an achromatic color to the display function layer; and
a controller which controls a driving of the pixel electrodes, the common electrode and the light source unit,
wherein
when a character is displayed in a first area of the display area, the controller applies a color other than the achromatic color to the first area, and makes a second area and a non-object area transparent,
the second area is an area other than the first area in an object area at least including an entire area of a row in which the first area is located,
the non-object area is an area other than the object area in the display area,
transparency of the non-object area is higher than transparency of the second area,
the object area has a rectangular area including continuous rows from a left end to a right end of the object area,
the non-object area has a rectangular area including other continuous rows from a left end to a right end of the non-object area, and adjoins the object area,
the display function layer is a liquid crystal layer using a polymer dispersed liquid crystal, and
the light source unit emits light from a side of the display panel into the display panel.

### Claim 2

A display device comprising:
a display panel comprising:
a plurality of pixel electrodes located in a display area, and provided in a plurality of rows;
a common electrode located in the display area; and
a display function layer located in the display area;
a light source unit located a non-display area outside the display area, and emitting light in a color other than an achromatic color to the display function layer; and
a controller which controls a driving of the pixel electrodes, the common electrode and the light source unit,
wherein
when a character is displayed in a first area of the display area, the controller applies a color other than the achromatic color to the first area, and makes a second area and a non-object area transparent,
the second area is an area other than the first area in an object area at least including an entire area of a row in which the first area is located,
the non-object area is an area other than the object area in the display area,
transparency of the non-object area is higher than transparency of the second area,
the pixel electrodes include a first pixel electrode located in the first area, a second pixel electrode located in the second area, and a third pixel electrode located in the non-object area,
the display function layer
includes a first display function layer to which voltage applied between the first pixel electrode and the common electrode is applied, a second display function layer to which voltage applied between the second pixel electrode and the common electrode is applied, and a third display function layer to which voltage applied between the third pixel electrode and the common electrode is applied, and
scatters incident light when scattering voltage is applied, maintains parallelism of incident light when first transparent voltage is applied, and maintains parallelism of incident light when second transparent voltage is applied,
parallelism of light passing through the display function layer when the second transparent voltage is applied is higher than parallelism of light passing through the display function layer when the first transparent voltage is applied,
a degree of scattering of light passing through the display function layer when the scattering voltage is applied is higher than a degree of scattering of light passing through the display function layer when the first transparent voltage is applied, and
when the character is displayed in the first area, the controller
applies the scattering voltage to the first display function layer,
applies the first transparent voltage to the second display function layer, and
applies the second transparent voltage to the third display function layer.

### Claim 3 (depends on 2)

The display device of claim 2, wherein
in a frame period of a period for displaying the character in the first area, the controller
drives the light source unit to irradiate the display function layer with light, and
applies the scattering voltage to the first display function layer, applies the first transparent voltage to the second display function layer and applies the second transparent voltage to the third display function layer while the display function layer is irradiated with light.

### Claim 4 (depends on 3)

The display device of claim 3, wherein
the light source unit comprises a first light-emitting element which emits light in a first color to the display function layer, a second light-emitting element which emits light in a second color to the display function layer, and a third light-emitting element which emits light in a third color to the display function layer,
the frame period comprises a first sub-frame period in which the first light-emitting element emits light in the first color, a second sub-frame period in which the second light-emitting element emits light in the second color, and a third sub-frame period in which the third light-emitting element emits light in the third color, and
the controller
applies the first transparent voltage to the second display function layer and applies the second transparent voltage to the third display function layer in all of the first sub-frame period, the second sub-frame period and the third sub-frame period, and
applies the scattering voltage to the first display function layer in at least one of the first sub-frame period, the second sub-frame period and the third sub-frame period.

### Claim 5 (depends on 4)

The display device of claim 4, wherein
the frame period further comprises a first reset period which is a head period of the frame period, and
in the first reset period, the controller applies the second transparent voltage to the first display function layer, the second display function layer and the third display function layer, and switches the light source unit to a turn-off state in which the display function layer is not irradiated with light.

### Claim 6 (depends on 5)

The display device of claim 5, wherein
the first frame period further comprises a second reset period between the first sub-frame period and the second sub-frame period, and a third reset period between the second sub-frame period and the third sub-frame period, and
in the second reset period and the third reset period, the controller applies the second transparent voltage to the first display function layer, the second display function layer and the third display function layer, and switches the light source unit to a turn-off state in which the display function layer is not irradiated with light.

### Claim 7 (depends on 2)

The display device of claim 2, wherein
the display panel further comprises a plurality of scanning lines extending in a row direction,
the first pixel electrode and the second pixel electrode are electrically connected to the same scanning line of the scanning lines, and
the third pixel electrode is electrically connected to another scanning line of the scanning lines.

### Claim 8 (depends on 2)

The display device of claim 2, wherein
the display function layer is a liquid crystal layer using a reverse mode polymer dispersed liquid crystal,
the scattering voltage comprises positive scattering voltage and negative scattering voltage, and
when the character is displayed in the first area, the controller alternately applies the positive scattering voltage and the negative scattering voltage to the first display function layer depending on each frame period.

### Claim 9 (depends on 8)

The display device of claim 8, wherein
when the character is displayed in the first area, the controller alternately applies positive first transparent voltage and negative first transparent voltage to the second display function layer depending on each frame period, and
when a highest degree of scattering of light entering the liquid crystal layer when each of the positive scattering voltage and the negative scattering voltage is applied to the liquid crystal layer is 100%, the positive first transparent voltage and the negative first transparent voltage are voltages in which the degree of scattering is less than or equal to 50%.

### Claim 10 (depends on 8)

The display device of claim 8, wherein
the second transparent voltage is 0 V.

### Claim 11

A display device comprising:
a display panel comprising:
a display area including a first area and a second area, the second area being an area other than the first area in an object area at least including an entire area of a row in which the first area is located;
a plurality of pixel electrodes including a first pixel electrode located in the first area and a second pixel electrode located in the second area, located in the display area, and provided in each of a plurality of rows;
a common electrode located in the display area; and
a liquid crystal layer including a first liquid crystal layer to which voltage applied between the first pixel electrode and the common electrode is applied and a second liquid crystal layer to which voltage applied between the second pixel electrode and the common electrode is applied, located in the display area, and using a reverse mode polymer dispersed liquid crystal;
a light source unit located a non-display area outside the display area, and emitting light to the liquid crystal layer; and
a controller which controls a driving of the pixel electrodes, the common electrode and the light source unit, wherein
when a character is displayed in the first area of the display area, the controller
applies scattering voltage to the first liquid crystal layer and scatters light entering the first liquid crystal layer, and
applies first transparent voltage to the second liquid crystal layer, maintains parallelism of light entering the second liquid crystal layer, and makes the second area transparent,
when a highest degree of scattering of light entering the liquid crystal layer when the scattering voltage is applied to the liquid crystal layer is 100%, the first transparent voltage is voltage in which the degree of scattering is less than or equal to 50%,
the object area has a rectangular area including continuous rows from a left end to a right end of the object area,
the non-object area has a rectangular area including other continuous rows from a left end to a right end of the non-object area, and adjoins the object area,
transparency of the non-object area is higher than transparency of the second area, and
the light source unit emits light from a side of the display panel into the display panel.

### Claim 12 (depends on 11)

The display device of claim 11, wherein
in a frame period of a period for displaying the character in the first area, the controller
drives the light source unit to irradiate the liquid crystal layer with light, and
applies the scattering voltage to the first liquid crystal layer, applies the first transparent voltage to the second liquid crystal layer and applies the second transparent voltage to the third liquid crystal layer while the liquid crystal layer is irradiated with light.

### Claim 13 (depends on 12)

The display device of claim 12, wherein
the light source unit comprises a first light-emitting element which emits light in a first color to the liquid crystal layer, a second light-emitting element which emits light in a second color to the liquid crystal layer, and a third light-emitting element which emits light in a third color to the liquid crystal layer,
the frame period comprises a first sub-frame period in which the first light-emitting element emits light in the first color, a second sub-frame period in which the second light-emitting element emits light in the second color, and a third sub-frame period in which the third light-emitting element emits light in the third color, and
the controller
applies the first transparent voltage to the second liquid crystal layer and applies the second transparent voltage to the third liquid crystal layer in all of the first sub-frame period, the second sub-frame period and the third sub-frame period, and
applies the scattering voltage to the first liquid crystal layer in at least one of the first sub-frame period, the second sub-frame period and the third sub-frame period.

### Claim 14 (depends on 13)

The display device of claim 13, wherein
the frame period further comprises a first reset period which is a head period of the frame period, and
in the first reset period, the controller applies the second transparent voltage to the first liquid crystal layer, the second liquid crystal layer and the third liquid crystal layer, and switches the light source unit to a turn-off state in which the liquid crystal layer is not irradiated with light.

### Claim 15 (depends on 14)

The display device of claim 14, wherein
the frame period further comprises a second reset period between the first sub-frame period and the second sub-frame period, and a third reset period between the second sub-frame period and the third sub-frame period, and
in the second reset period and the third reset period, the controller applies the second transparent voltage to the first liquid crystal layer, the second liquid crystal layer and the third liquid crystal layer, and switches the light source unit to a turn-off state in which the liquid crystal layer is not irradiated with light.

### Claim 16 (depends on 11)

The display device of claim 11, wherein
the display panel further comprises a plurality of scanning lines extending in a row direction,
the first pixel electrode and the second pixel electrode are electrically connected to the same scanning line of the scanning lines, and
the third pixel electrode is electrically connected to another scanning line of the scanning lines.

### Claim 17 (depends on 12)

The display device of claim 12, wherein
the scattering voltage comprises positive scattering voltage and negative scattering voltage, and
when the character is displayed in the first area, the controller alternately applies the positive scattering voltage and the negative scattering voltage to the first liquid crystal layer depending on each frame period.

### Claim 18 (depends on 17)

The display device of claim 17, wherein
when the character is displayed in the first area, the controller alternately applies positive first transparent voltage and negative first transparent voltage to the second liquid crystal layer depending on each frame period, and
when a highest degree of scattering of light entering the liquid crystal layer when each of the positive scattering voltage and the negative scattering voltage is applied to the liquid crystal layer is 100%, the positive first transparent voltage and the negative first transparent voltage are voltages in which the degree of scattering is less than or equal to 50%.

### Claim 19 (depends on 17)

The display device of claim 17, wherein
the second transparent voltage is 0 V.