Display with continuous profile peak luminance control

• US 10,089,959 B2
• Filed: 09/29/2015
• Issued: 10/02/2018
• Est. Priority Date: 04/24/2015
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Jangda, Mohammad Ali, Aflatooni, Koorosh, Bi, Yafei
• Primary Examiner(s): Li, Lin
• Application Number:
  US14/869,437
• Publication Number:
  US 20160314760A1
• Time in Patent Office: 1,099 Days
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0653 Controlling or limiting the speed of brightness adjustment of the illumination source
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/028 Generation of voltages supplied to electrode drivers in a matrix display other than LCD
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3208 organic, e.g. using organic light-emitting diodes [OLED]

Abstract

A display may have an array of display pixels. Digital display data may be received by a digital-to-analog converter that converts the digital display data to analog display data. The magnitudes of the analog display data signals can be controlled by a regulated voltage received by the digital-to-analog converter. A brightness controller may have multiple peak luminance control (PLC) profiles. In accordance with an embodiment, a brightness setting may be processed by a lookup table to identify a pair of PLC profiles that is interpolated in order to obtain the desired regulated voltage. In accordance with another embodiment, a single PLC profile may be used that is a function of a combined parameter that takes into account both average frame luminance and the brightness setting. In accordance with yet another embodiment, a lookup table that specifies brightness setting offset values may be used to directly modulate the brightness setting.

Claims

1. Display circuitry, comprising:

an array of display pixels; and

display control circuitry that displays images on the array of display pixels, wherein the display control circuitry includes;

a gamma reference block having an input that receives digital data for the images, an output that supplies corresponding analog data signals for the images to columns of display pixels in the array, and a power supply terminal that receives a regulated voltage;

a brightness control block that performs interpolation between selected first and second peak luminance control (PLC) profiles to obtain an interpolated lookup table listing interpolated voltage settings that control the regulated voltage for the gamma reference block; and

a peak luminance control (PLC) profile lookup table that receives a display brightness setting and that identifies the selected first and second PLC profiles from among at least three PLC profiles based on the received display brightness setting, wherein the selected first PLC profile is a function of a given range of average pixel level values, and wherein the selected second PLC profile is also a function of the given range of average pixel level values, wherein the brightness control block comprises a peak luminance control (PLC) circuit that receives the selected first and second PLC profiles and an average pixel value and that outputs a peak luminance scaling factor, wherein brightness control block further comprises a first data converter controlled by the peak luminance scaling factor, wherein the brightness control block further comprises a second data converter coupled in series with the first data converter, and wherein the second data converted is controlled by the received display brightness setting.

2. The display circuitry defined in claim 1, wherein the display control circuitry further comprises:

an average picture level calculator that receives the digital data and that outputs a corresponding average picture level value for one of the images to the brightness control block, wherein the received display brightness setting is a user-selected brightness setting.

3. The display circuitry defined in claim 2, wherein the interpolated lookup table is used to determine the value of the regulated voltage as a function of the average picture level value output from the average picture level calculator.

4. The display circuitry defined in claim 2, wherein the display brightness control block includes an average picture level (APL) lookup table that lists first voltage settings as a function of the average picture level value for the first PLC profile and that lists second voltage settings as a function of the average picture level value for the second PLC profile, and wherein entries in the interpolated lookup table are computed by interpolating between the first and second voltage settings in the APL lookup table.

5. The display circuitry defined in claim 2, wherein the first PLC profile configures the brightness control block to initiate dimming at a first average picture level value, and wherein the second PLC profile configures the brightness control block to initiate dimming at a second average picture level value that is different than the first average pixel picture level.

6. The display circuitry defined in claim 1, wherein the PLC profile lookup table is configured to identify the selected first and second PLC profiles from among the plurality of PLC profiles for the interpolation when the received display brightness setting falls in a first display brightness interval and is also configured to identify two other PLC profiles from among the plurality of PLC profiles for the interpolation when the received display brightness setting falls in a second display brightness interval that is different than the first display brightness interval.

7. The display circuitry defined in claim 1, wherein the brightness control block is configured to compute values for the interpolated lookup table on-the-fly in response to the display brightness setting being changed.

8. A method of operating a display having display control circuitry that displays images on an array of display pixels, comprising:

receiving digital data for the images and calculating an average pixel luminance value for one of the images using the display control circuitry;

receiving a display brightness setting at the display control circuitry;

computing a combined parameter that is a function of both the calculated average pixel luminance value and the received display brightness setting, wherein the combined parameter is a product of the calculated average pixel luminance value and a factor that is proportional to the received display brightness setting, wherein computing the combined parameter comprises computing a first value by calculating the difference between a predetermined minimum brightness setting and the received display brightness setting, wherein computing the combined parameter further comprises computing a second value by calculating the difference between the predetermined minimum brightness setting and a predetermined maximum brightness setting, and wherein computing the combined parameter further comprises dividing the first value by the second value to obtain a third value; and

using the combined parameter to identify a corresponding voltage setting in a peak luminance control (PLC) lookup table to control the brightness of the display.

9. The method defined in claim 8, wherein the PLC lookup table includes voltage settings for only a single peak luminance control profile that species a particular threshold level for the combined parameter at which dimming should be initiated.

10. The method defined in claim 8, further comprising:

in response to detecting a change in the display brightness setting, recomputing the combined parameter to identify another voltage setting in the PLC lookup table that is used to adjust the brightness of the display.

11. The method defined in claim 8, wherein computing the combined parameter further comprises multiplying the third value by the calculated average pixel luminance value.