Backlight for a display

• US 9,208,709 B2
• Filed: 05/05/2010
• Issued: 12/08/2015
• Est. Priority Date: 05/05/2010
• Status: Expired due to Fees

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Merz, Nicholas George
• Primary Examiner(s): Wang, Quan-Zhen
• Assistant Examiner(s): DAVIS, TONY O
• Application Number:
  US12/774,139
• Publication Number:
  US 20110273377A1
• Time in Patent Office: 2,043 Days
• Field of Search: 345/173, 345/76, 345/102
• US Class Current: 1/1
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: 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
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 5/003 Details of a display terminal, the details relating to the control arrangement of the display terminal and to the interfaces thereto specific for a CRT G09G1/165; for a flat panel G09G3/2092

Abstract

Systems and devices are provided for using an organic light emitting diode (OLED) as a backlight for a liquid crystal display (LCD) device. In one embodiment, an OLED backlight may include one or more OLED elements disposed between two substrates. The OLED backlight may be optically bonded to the back of an LCD, and may further be electrically connected with the LCD active matrix. In one embodiment, information transmitted to selected pixels of the LCD active matrix may also be used by elements of the OLED backlight which are electrically connected to the selected LCD pixels. For example, the OLED backlight may respond to grayscale information transmitted to selected LCD pixels by emitting a corresponding intensity of light. In some embodiments, the LCD device may include other functions, such as touch sensing capabilities, which may be integrated with the LCD and OLED backlight.

Claims

1. A liquid crystal display (LCD) device, comprising:

an organic light emitting diode (OLED) device comprising a plurality of elements disposed between a substrate layer and a cover layer, and a bond disposed about a periphery of the OLED device, wherein the plurality of elements is configured to receive an emission signal generated by a processor and emit light at an intensity based on the emission signal;

an optically clear adhesive layer comprising a first face and an opposing second face, wherein the first face is optically bonded to the OLED device; and

an active matrix comprising a plurality of active matrix pixels formed in a TFT layer, wherein the plurality of active matrix pixels is configured to receive an image signal generated by the processor and to modulate the transmission of the emitted light based on the image signal, wherein the TFT layer with the active matrix is optically bonded to the second face of the optically clear adhesive layer, the TFT layer is directly bonded to the OLED device via the optically clear adhesive layer, and wherein each of the plurality of active matrix pixels is configured to modulate the transmission of the emitted light from at least one respective element of the plurality of elements.

2. The LCD device of claim 1, wherein each of the plurality of active matrix pixels is configured to modulate the transmission of the emitted light from a corresponding one of the plurality of elements, and wherein each of the plurality of active matrix pixels comprise a red pixel, a blue pixel, and a green pixel.

3. The LCD device of claim 1, wherein the active matrix is configured to modulate the transmission between substantially blocking the emitted light and substantially transmitting the emitted light, and wherein the intensity of the emitted light is low when the active matrix is substantially blocking, relative to the intensity of the emitted light when the active matrix is substantially transmitting.

4. The LCD device of claim 1, wherein the intensity of the emitted light is based at least in part on the image signal.

5. The LCD device of claim 1, wherein each of the plurality of active matrix pixels is configured to modulate the transmission of the emitted light from a corresponding pair of the plurality of elements, wherein each of the plurality of active matrix pixels comprise a red pixel, a blue pixel, and a green pixel, and wherein each element of the pair of the plurality of elements is differentially driven based on wear considerations.

6. The LCD device of claim 1, wherein the LCD device comprises a touchscreen integrally formed with the active matrix, wherein the touchscreen is configured to respond to a user touch, and wherein the OLED device is configured to emit light at an intensity based on the user touch, and wherein the active matrix is configured to modulate the transmission of the emitted light based on the user touch.

7. The LCD device of claim 1, wherein the image signal is calibrated based on the intensity of the emitted light.

8. The LCD device of claim 1, wherein the processor is configured to generate a data signal comprising the image signal and the emission signal, wherein the image signal is addressed to the plurality of active matrix pixels, and wherein the emission signal is addressed to the plurality of elements.

9. The LCD device of claim 1, comprising a black layer disposed behind the LCD device.

10. An electronic device, comprising:

a touchscreen integrally formed with a light modulating layer, wherein the touchscreen is configured to receive a touch input and is configured to change a displayed screen on the electronic device in response to the touch input;

a processor configured to generate an image signal and an emission signal based on the touch input;

an organic light emitting diode (OLED) backlight configured to emit light based on the emission signal;

the light modulating layer configured to modulate the transmission of the emitted light based on the image signal, wherein the light modulating layer comprises a thin film transistor (TFT) layer; and

an optically clear adhesive layer optically bonded to the OLED backlight and to the TFT layer of the light modulating layer, wherein the OLED backlight is directly bonded to the TFT layer via the optically clear adhesive layer.

11. The display device of claim 10, wherein the light modulating layer comprises a liquid crystal layer, wherein the TFT layer is configured to generate an electric field based on the image signal and the liquid crystal layer is configured to transmit a range of the emitted light based on the electric field.

12. The display device of claim 10, wherein the OLED backlight comprises one OLED element.

13. The display device of claim 10, wherein the OLED backlight comprises a plurality of OLED elements and the light modulating layer comprises a plurality of pixels, wherein each of the pixels is configured to modulate the transmission of the emitted light from each of the plurality of elements.

14. The display device of claim 10, wherein the OLED backlight comprises a plurality of OLED elements and the light modulating layer comprises a plurality of pixels, wherein each of the pixels is configured to modulate the transmission of the emitted light from an element pair of the plurality of OLED elements, and wherein each OLED element of the element pair is alternately activated.

15. The display device of claim 10, wherein the processor is configured to generate a data signal comprising the image signal and the emission signal, wherein the image signal is addressed to the light modulating layer, and wherein the emission signal is addressed to the OLED backlight.

16. The display device of claim 10, wherein the emission signal results in the OLED backlight emitting light at an intensity corresponding to the transmission of light based on the image signal.

17. An electronic system, comprising:

a processor configured to generate a data signal comprising an image signal and an emission signal; and

a display comprising;

a backlight assembly comprising a plurality of organic light emitting diode (OLED) elements configured to emit light at an intensity according to the emission signal; and

a light modulating layer optically bonded to the backlight assembly, wherein the light modulating layer comprises a thin film transistor (TFT) layer directly bonded with the backlight assembly, the light modulating layer comprises a plurality of light modulating pixels configured to transmit the emitted light at a transmission percentage according to the image signal, and each of the plurality of OLED elements is electrically connected to a respective one of the plurality of light modulating pixels.

18. The electronic system of claim 17, comprising a bus configured to transmit the data signal to the connection between each of the plurality of OLED elements and the respective one of the plurality of light modulating pixels, wherein the emission signal is addressed to each of the plurality of OLED elements and the image signal is addressed to the respective one of the plurality of light modulating pixels.

19. The electronic system of claim 17, comprising a sensor configured to measure an intensity of light emitted by the plurality of OLED elements, wherein the processor is configured to determine an intensity ratio of the measured light intensity relative to the emission signal and configured to calibrate the image signal based on the emission signal and the intensity ratio.

20. The electronic system of claim 19, wherein the processor is configured to generate an image signal such that the light modulating layer transmits the emitted light at an increased transmission percentage, wherein the increased transmission percentage is inversely related to a decrease between the determined intensity ratio and a threshold intensity ratio.

21. The electronic system of claim 17, comprising a touchscreen configured to respond to a user touch, and wherein the backlight assembly is configured to emit light at an intensity based on the user touch, and wherein the light modulating layer is configured to modulate the transmission of the emitted light based on the user touch.

22. The electronic system of claim 17, comprising a light sensor configured to generate a sensor signal in response to sensed ambient light, wherein the OLED elements are configured to emit light at an intensity according to the sensor signal.

23. The electronic system of claim 22, wherein the light sensor is a photovoltaic sensor coupled in series with a diode gate of the OLED element.