ELECTROLUMINESCENT DISPLAY DEVICE INTEGRATED WITH IMAGE SENSOR

• US 20180151656A1
• Filed: 11/08/2017
• Published: 05/31/2018
• Est. Priority Date: 11/25/2016
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: CHOO, Kyoseop, LEE, Guensik, HAN, Manhyeop
• Granted Patent: US 10,714,554 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 2203/04109 FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location
• CPC Class Codes: G06V 40/1318 using electro-optical elements or layers, e.g. electroluminescent sensing
• CPC Class Codes: G09G 2300/0814 used for selection purposes, e.g. logical AND for partial update
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2310/0256 with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/04 Maintaining the quality of display appearance
• CPC Class Codes: G09G 2360/14 Detecting light within display terminals, e.g. using a single or a plurality of photosensors
• CPC Class Codes: G09G 2360/148 the light being detected by light detection means within each pixel
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: H10K 59/1201 Manufacture or treatment
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs
• CPC Class Codes: H10K 59/1216 the pixel elements being capacitors
• CPC Class Codes: H10K 59/351 comprising more than three subpixels, e.g. red-green-blue-white [RGBW]

Abstract

Disclosed is an electroluminescent display device integrated with image sensors, including: a display panel having a plurality of pixels; a display panel driving circuit configured to write data of an input image into the pixels during a display mode so as to display the input image with the pixels; and a sensor processing circuit configured to apply a reverse bias to Organic Light Emitting Diodes (OLEDs) disposed in at least some of the pixels during a sensor mode so as to process sensor signals received from the pixels.

Claims

1. An electroluminescent display device, comprising:

a display panel having a plurality of pixels, each of the pixels including an Organic Light Emitting Diode (OLED);

a display panel driving circuit configured to write data of an input image into the pixels during a display mode so as to display the input image with the pixels; and

a sensor processing circuit configured to apply a reverse bias to the OLEDs of at least some of the pixels during a sensor mode so as to process sensor signals received from the pixels.

2. The electroluminescent display device of claim 1, wherein the sensor processing circuit increases a cathode voltage of the OLEDs in the sensor mode.

3. The electroluminescent display device of claim 1,

wherein, in the display mode, a threshold voltage of a driving element formed in each of the pixels is sampled during a display mode programming period, and

wherein, in the sensor mode, a sensor mode programming period is divided into a first period, in which a sensor signal is charged in capacitors connected to anodes of the OLEDs, and a second period, in which the signal charged in the capacitors is transmitted to the sensor signal processing circuit.

4. The electroluminescent display device of claim 3, wherein the display mode programming period and the sensor mode programming period have a same duration during one horizontal period.

5. The electroluminescent display device of claim 1, wherein, in the sensor mode, OLEDs of a first portion of pixels arranged in a sensing area of the display panel emit light in response to a forward bias to thereby operate as light source pixels, and OLEDs of a second portion of pixels arranged in the sensing area operate as sensor pixels in response to a reverse bias.

6. The electroluminescent display device of claim 5, wherein locations of the light source pixels and the sensor pixels shift temporally.

7. The electroluminescent display device of claim 1,

wherein the pixels are divided into M×

N pixel groups (each of M and N is a positive integer equal to or greater than

     3),

wherein a pixel located at a central region of a M×

N pixel group operates as a sensor pixel, and pixels surrounding the sensor pixel operate as a light source pixels, and

wherein locations of the M×

N pixel groups shift temporally.

8. The electroluminescent display device of claim 1, further comprising:

a transparent substrate disposed on the display panel;

a light source disposed along an edge of the transparent substrate;

a light entrance element disposed between the light source and the transparent substrate, and configured to refract incident light into the transparent substrate as propagating light at a total reflectance angle;

a light exit element disposed on a same plane as the light entrance element, and configured to refract part of the propagating light in the transparent substrate toward the display panel through a bottom surface of the transparent substrate; and

a low refractive layer disposed between the light exit element and the display panel, and having a refractive index smaller than a refractive index of the light exit element.

9. The electroluminescent display device of claim 8, wherein a reverse bias is applied to all pixels on the display panel in the sensor mode.

10. The electroluminescent display device of claim 1, wherein the pixels sense at least one of a fingerprint pattern or a document image in the sensor mode.