PATENT DOCUMENT

Publication Number: US-10354617-B2
Application Number: US-201715839660-A
Country: US
Kind Code: B2

Title: Luminescence shock avoidance in display devices

Abstract:
A luminescence shock avoidance algorithm selectively limits the brightness level of a display device when the display device is activated in a dark environment to prevent the temporary vision impairment that can occur when a display device is activated in a dark environment. The algorithm receives the state of the display (e.g. on or in standby mode), and can optionally receive an ambient lighting value from an ambient light sensor and a user-selectable manual brightness adjustment setting to determine whether luminescence shock avoidance should even be triggered, and if it is triggered, how much should the brightness level of the display be limited.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a display; 
 an ambient light sensor that detects an ambient light level while the display is off, wherein the display is at a zero brightness level while the display is off; and 
 control circuitry that increases a brightness of the display from the zero brightness level based on the detected ambient light level when the display is turned on. 
 
     
     
       2. The electronic device defined in  claim 1 , wherein the control circuitry increases the brightness of the display from the zero brightness level to a first brightness level when the detected ambient light level is below a threshold. 
     
     
       3. The electronic device defined in  claim 2 , wherein the control circuitry increases the brightness of the display from the zero brightness level to a second brightness level when the detected ambient light level is above the threshold, and wherein the second brightness level is greater than the first brightness level. 
     
     
       4. The electronic device defined in  claim 3 , wherein the control circuitry increases the brightness of the display based on a brightness adjustment function, and wherein the second brightness level is equal to a first normal brightness level determined by the brightness adjustment function for the detected ambient light level that is above the threshold. 
     
     
       5. The electronic device defined in  claim 4 , wherein the brightness adjustment function is selected by a user of the electronic device. 
     
     
       6. The electronic device defined in  claim 4 , wherein the second brightness level is less than a second normal brightness level determined by the brightness adjustment function for the detected ambient light level that is below the threshold and wherein the control circuitry increases the brightness of the display from the second brightness level to the second normal brightness level after a predetermined period of time. 
     
     
       7. A method of operating an electronic device having a display, the method comprising:
 with an ambient light sensor, producing ambient light data while the display is powered-down; and 
 with control circuitry, activating the display by adjusting a brightness level of the display from a zero brightness level while the display is powered-down to a non-zero brightness level while the display is activated based on the ambient light data. 
 
     
     
       8. The method defined in  claim 7 , wherein the ambient light data is based on a detected ambient light level, activating the display further comprising:
 increasing the brightness level of the display from the zero brightness level to the non-zero brightness level when the detected ambient light level is below a threshold. 
 
     
     
       9. The method defined in  claim 8 , wherein the non-zero brightness level is a first non-zero brightness level, activating the display further comprising:
 increasing the brightness of the display from the zero brightness level to a second non-zero brightness level when the detected ambient light level is above the threshold, wherein the second non-zero brightness level is greater than the first non-zero brightness level. 
 
     
     
       10. The method defined in  claim 9 , activating the display further comprising:
 increasing the brightness of the display based on a brightness adjustment function, wherein the second non-zero brightness level is equal to a first normal brightness level determined by the brightness adjustment function for the detected ambient light level that is above the threshold. 
 
     
     
       11. The method defined in  claim 10 , wherein the brightness adjustment function is selected by a user of the electronic device. 
     
     
       12. The method defined in  claim 10 , wherein the second non-zero brightness level is less than a second normal brightness level determined by the brightness adjustment function for the detected ambient light level that is below the threshold. 
     
     
       13. The method defined in  claim 12 , further comprising:
 increasing the brightness of the display from the second non-zero brightness level to the second normal brightness level after a predetermined period of time. 
 
     
     
       14. An electronic device, comprising:
 a display; 
 a sensor that produces sensor data while the display is turned off; and 
 control circuitry that measures an ambient light level based on the sensor data and turns the display on based on the ambient light level. 
 
     
     
       15. The electronic device defined in  claim 14 , wherein the sensor is an ambient light sensor and wherein the sensor data is ambient light sensor data. 
     
     
       16. The electronic device defined in  claim 15 , wherein when the measured ambient light level is above a threshold, the control circuitry turns the display on to a brightness level that is determined based on a user-selectable brightness setting and a brightness function. 
     
     
       17. The electronic device defined in  claim 16 , wherein the brightness level is a first brightness level, and wherein when the measured ambient light level is below the threshold, the control circuitry turns the display on to a second brightness level that is determined based on a reduced brightness function but not the user-selectable brightness setting. 
     
     
       18. The electronic device defined in  claim 16 , wherein the brightness level is a first brightness level, and wherein when the measured ambient light level is below a threshold, the control circuitry turns the display on to a second brightness level that is determined based on a reduced brightness function and the user-selectable brightness setting. 
     
     
       19. The electronic device defined in  claim 16 , wherein the brightness function is determined based on the user-selectable brightness setting. 
     
     
       20. An electronic device, comprising:
 a display; 
 an ambient light sensor that detects an ambient light level; and 
 control circuitry that increases a brightness of the display from a zero brightness level based on a comparison between the detected ambient light level and a threshold.

Description:
This application is a continuation of U.S. patent application Ser. No. 15/258,937, filed Sep. 7, 2016, which is a continuation of U.S. patent application Ser. No. 14/793,627, filed Jul. 7, 2015, now U.S. Pat. No. 9,443,460, which is a continuation of U.S. patent application Ser. No. 14/279,746, filed May 16, 2014, now U.S. Pat. No. 9,082,336, issued Jul. 14, 2015, which is a continuation of U.S. patent application Ser. No. 13/777,072, filed Feb. 26, 2013, now U.S. Pat. No. 8,743,161, issued Jun. 3, 2014, which is a continuation of U.S. patent application Ser. No. 13/304,176, filed Nov. 23, 2011, now U.S. Pat. No. 8,405,688, issued Mar. 26, 2013, which is a continuation of U.S. patent application Ser. No. 11/800,293, filed May 4, 2007, now U.S. Pat. No. 8,068,125, issued Nov. 29, 2011, which claims priority to U.S. provisional patent application No. 60/878,755, filed on Jan. 5, 2007, each of which is hereby incorporated by reference herein in its entirety. This application claims the benefit of and claims priority to U.S. patent application Ser. No. 15/258,937, filed Sep. 7, 2016, U.S. patent application Ser. No. 14/793,627, filed Jul. 7, 2015, now U.S. Pat. No. 9,443,460, U.S. patent application Ser. No. 14/279,746, filed May 16, 2014, now U.S. Pat. No. 9,082,336, issued Jul. 14, 2015, U.S. patent application Ser. No. 13/777,072, filed Feb. 26, 2013, now U.S. Pat. No. 8,743,161, issued Jun. 3, 2014, U.S. patent application Ser. No. 13/304,176, filed Nov. 23, 2011, now U.S. Pat. No. 8,405,688, issued Mar. 26, 2013, U.S. patent application Ser. No. 11/800,293, filed May 4, 2007, now U.S. Pat. No. 8,068,125, issued Nov. 29, 2011, and U.S. provisional patent application No. 60/878,755, filed on Jan. 5, 2007. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to display devices, and more particularly, to avoiding luminescence shock (temporary vision impairment) when a display device is activated in a dark environment. 
     BACKGROUND 
     Many types of input devices are presently available for performing operations in a computing system, such as buttons or keys, mice, trackballs, touch panels, joysticks, touch screens and the like. Touch screens, in particular, are becoming increasingly popular because of their ease and versatility of operation as well as their declining price. Touch screens can include a touch sensor panel, which can be a clear panel with a touch-sensitive surface. The touch sensor panel can be positioned in front of a display screen so that the touch-sensitive surface covers the viewable area of the display screen. Touch screens can allow a user to make selections and move a cursor by simply touching the display screen via a finger or stylus. In general, the touch screen can recognize the touch and position of the touch on the display screen, and the computing system can interpret the touch and thereafter perform an action based on the touch event. 
     Because touch screens can reduce or eliminate the need for physical keypads or buttons, the touch screens themselves can often be made larger in comparison to the overall size of the device. These larger touch screens have enabled even small devices such as personal digital assistants (PDAs), mobile telephones, digital audio/video players, and the like to provide a wider variety of content than previously possible, including video, graphics, Internet access, photos, and the like. The convenience of today&#39;s handheld portable devices combined with their ever-increasing multi-media functionality has made such devices seemingly ubiquitous, with users carrying them everywhere, in purses or clipped to belts. To a dedicated user, these personal devices can be as indispensable as a wallet. To that end, users may place these personal devices within arms reach wherever they go, including vehicles, movie theaters, and the like. 
     Because personal devices tend to have small batteries, power savings is critical. A large display illuminated to full brightness will exhaust a battery in no time, and thus power saving functions such as sleep modes are common in personal devices. For example, the display of a mobile telephone may be dimmed or go dark altogether until a call is received, or the screen of a PDA may go blank until the user activates a function or a communication such as an e-mail or text message is received. However, if one of these personal devices is in a sleep mode in a dark environment and the display is suddenly illuminated due to a received call or other communication, a nearby user who happens to be looking at the device or is instinctively drawn to looking at the display when it illuminates can suffer temporary vision impairment. Because the user&#39;s pupils have opened up in the dark environment, the sudden flash of light can cause short-term blindness or at least impaired vision. This temporary impaired vision can range from a mere annoyance to a life-threatening situation if the user is driving a motor vehicle. 
     SUMMARY 
     A luminescence shock avoidance algorithm can be employed to selectively limit the brightness level of a display device when the display device is activated in a dark environment to prevent the temporary vision impairment that can occur when a display device is activated in a dark environment. The algorithm receives the state of the display (e.g. on or in standby mode), and can optionally receive an ambient lighting value from an ambient light sensor and a user-selectable manual brightness adjustment setting to determine whether luminescence shock avoidance should even be triggered, and if it is triggered, how much should the brightness level of the display be limited. 
     When a display device is in a standby, sleep or powered-down mode to save battery power, the display is at a zero brightness level. When the display is automatically activated, such as when a telephone call is received, the display can turn on to a brightness level determined by the ambient light level detected by the ambient light sensor. If the device is in a car being driven at night, for example, then when a call or other triggering activity is detected, the display brightness level may instantly jump from zero to some predetermined level. Because the user&#39;s eyes are likely to be already adjusted to the darkness of the car, the sudden change in display brightness level from can cause luminescence shock and temporary vision impairment, which can be dangerous to the operator of the car, especially if the driver takes a glance at the newly illuminated display. 
     To avoid luminescence shock, if the display device is off and a call or other triggering activity is detected, the ambient light sensor will turn on and detect a certain ambient light level. In one embodiment, if the detected ambient light level is greater than or equal to a threshold value, then the display device will turn on at a brightness level according to the current display brightness setting. In other words, if the ambient light level is greater than or equal to threshold value, the display will turn on from a zero brightness level to the level defined by the appropriate brightness function as determined by the current display brightness setting. Because the threshold value is chosen such that no luminescence shock is expected for ambient light levels above the threshold value, no adjustment is made to the display brightness level when the display turns on. 
     However, if the detected ambient light level is below the threshold value, luminescence shock may occur, so the display device will turn on from a zero brightness level to an initially reduced brightness level as compared to what would normally be expected if the brightness function appropriate for the current display brightness level was followed. In other words, the display will initially turn on to a brightness level less than the appropriate brightness function as determined by the current display brightness setting. This dimmer than usual brightness level is intended to avoid luminescence shock. After some short time period has passed, giving the user&#39;s eyes time to adjust, the brightness level can be gradually or instantly increased to the level determined by the appropriate brightness function, which should be closer to ideal for sufficient visibility at the current ambient light level. 
     In other embodiments, a threshold is not used, and therefore regardless of the detected ambient light level, the display will initially turn on to a brightness level less than the appropriate brightness function as determined by the current display brightness setting. Optionally, as above, after some short time period has passed, the brightness level can be gradually or instantly increased to the level determined by the appropriate brightness function. 
     If the display device is already on and a call or other triggering activity is detected, there will be no change to the display brightness, regardless of the current light level. In other words, the luminescence shock avoidance algorithm can be employed only when the display device is initially off. 
     The reduced brightness value may be implemented in a number of different ways. If the detected ambient light level is below a threshold, the reduced display brightness value may be a fixed value, regardless of the current display brightness settings. After some short time period has passed, the brightness level can be gradually or instantly increased to the level determined by the brightness function appropriate for the current display brightness settings. Alternatively, the reduced display brightness value can be a fixed value that is dependent on the current display brightness settings. In another embodiment, the reduced display brightness value is dependent only on the detected ambient light level, regardless of the current display brightness settings. In still other embodiments, the reduced display brightness value is dependent both on the detected ambient light level and the current display brightness settings. 
     Even in embodiments without an ambient light sensor, and therefore no detected ambient light level, luminescence shock can be avoided. When a telephone call or other triggering activity is detected, the display may initially come on with a reduced brightness value as compared to normal levels. After some short time period has passed, the brightness level can be gradually or instantly increased to normal levels. 
     In other embodiments, the wavelength of light from the display can be shifted to further reduce luminescence shock. If ambient light levels below a certain threshold are detected when a telephone call or other activity is detected and the display is turned on, the color of the display can be temporarily gamma-shifted into the red region, either alone or in combination with reduced display brightness levels as described above. By gamma-shifting the display towards red light, the brightness of the display will tend to cause the user&#39;s pupils to constrict less, so that when the user looks up again at a dark road, for example, the user&#39;s vision impairment is reduced. If gamma-shifting is applied in combination with reduced display brightness levels, the display brightness levels may not need to be reduced as much. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an exemplary computing system including a display device operable in accordance with a luminescence shock avoidance algorithm according to one embodiment of this invention. 
         FIG. 2 a    illustrates exemplary brightness functions of ambient light (in lux (one lumen per square meter)) vs. display device brightness or luminance (in nits (one candela per square meter)) for an exemplary display device according to one embodiment of this invention. 
         FIG. 2 b    illustrates a luminescence shock avoidance algorithm wherein if the detected ambient light level is below a threshold, the reduced display brightness value may be a fixed value regardless of the current display brightness settings according to one embodiment of this invention. 
         FIG. 2 c    illustrates a luminescence shock avoidance algorithm wherein if the detected ambient light level is below a threshold, the reduced display brightness value is a fixed value that is dependent on the current display brightness settings according to one embodiment of this invention. 
         FIG. 2 d    illustrates a luminescence shock avoidance algorithm wherein if the detected ambient light level is below a threshold, the reduced display brightness value is dependent only on the detected ambient light level, regardless of the current display brightness settings according to one embodiment of this invention. 
         FIG. 2 e    illustrates a luminescence shock avoidance algorithm wherein if the detected ambient light level is below a threshold, the reduced display brightness value is dependent both on the detected ambient light level and the current display brightness settings according to one embodiment of this invention. 
         FIG. 2 f    illustrates a luminescence shock avoidance algorithm in which no ambient light level is detected and the display device initially turns on at a reduced brightness level before ramping up to normal levels according to one embodiment of this invention. 
         FIG. 3  is a plot of wavelength vs. pupil sensitivity, showing that the pupils are more sensitive to blue/green light as compared to red light to illustrate the purpose of gamma-shifting according to one embodiment of this invention. 
         FIG. 4  is a more detailed view of the host processor, ambient light sensor and display device shown in  FIG. 1  according to one embodiment of this invention. 
         FIG. 5 a    illustrates an exemplary mobile telephone that can include luminescence shock avoidance algorithms according to one embodiments of this invention. 
         FIG. 5 b    illustrates an exemplary digital audio player that can include luminescence shock avoidance algorithms according to one embodiments of this invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description of preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which it is shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the preferred embodiments of the present invention. 
     A luminescence shock avoidance algorithm can be employed to selectively limit the brightness level of a display device when the display device is activated in a dark environment to prevent the temporary vision impairment that can occur when a display device is activated in a dark environment. The algorithm receives the state of the display (e.g. on or in standby mode), and can optionally receive an ambient lighting value from an ambient light sensor and a user-selectable manual brightness adjustment setting to determine whether luminescence shock avoidance should even be triggered, and if it is triggered, how much should the brightness level of the display be limited. 
     Although some embodiments of this invention may be described herein in terms of mobile telephones, it should be understood that other embodiments of this invention may not be so limited, but can be generally applicable to any display device that is capable of automatically waking up from a sleep mode and illuminating the display to a certain level. 
       FIG. 1  illustrates exemplary computing system  100  operable with touch screen  142  formed from sensor panel  124  and display device  140  that may be used in conjunction with embodiments of this invention. However, it should be understood that the system of  FIG. 1  is merely illustrative of a number of different touch screen systems that can be used with embodiments of this invention. 
     Sensor panel  124  can include a capacitive touch sensor panel capable of detecting touch or hovering within the near-field detection capabilities of the capacitive touch sensors, or a proximity sensor panel capable of detecting hovering outside the near field detection capabilities of the capacitive touch sensors, or a combination of both. Examples of a capacitive touch sensor panel and a proximity sensor panel are described in Applicant&#39;s co-pending U.S. application Ser. No. 11/649,998 entitled “Proximity and Multi-Touch Sensor Detection and Demodulation,” filed on Jan. 3, 2007, the contents of which are incorporated by reference herein. 
     Sensor panel  124  can be connected to other components in computing system  100  through connectors integrally formed on the sensor panel, or using flex circuits. Computing system  100  can include one or more panel processors  102  and peripherals  104 , and panel subsystem  106 . The one or more processors  102  can include, for example, ARM968 processors or other processors with similar functionality and capabilities. However, in other embodiments, the panel processor functionality can be implemented instead by dedicated logic such as a state machine. Peripherals  104  can include, but are not limited to, random access memory (RAM) or other types of memory or storage, watchdog timers and the like. 
     Panel subsystem  106  can include, but is not limited to, one or more analog channels  108 , channel scan logic  110  and driver logic  114 . Channel scan logic  110  can access RAM  112 , autonomously read data from the analog channels and provide control for the analog channels. This control can include multiplexing columns of sensor panel  124  to analog channels  108 . In addition, channel scan logic  110  can control the driver logic and stimulation signals being selectively applied to rows of sensor panel  124 . In some embodiments, panel subsystem  106 , panel processor  102  and peripherals  104  can be integrated into a single application specific integrated circuit (ASIC). 
     Driver logic  114  can provide multiple panel subsystem outputs  116  and can present a proprietary interface that drives high voltage driver  118 . High voltage driver  118  can provide level shifting from a low voltage level (e.g. complementary metal oxide semiconductor (CMOS) levels) to a higher voltage level, providing a better signal-to-noise (S/N) ratio for noise reduction purposes. The high voltage driver outputs can be sent to decoder  120 , which can selectively connect one or more high voltage driver outputs to one or more panel row inputs  122  through a proprietary interface and enable the use of fewer high voltage driver circuits in the high voltage driver  118 . Each panel row input  122  can drive one or more rows in sensor panel  124 . In some embodiments, high voltage driver  118  and decoder  120  can be integrated into a single ASIC. However, in other embodiments high voltage driver  118  and decoder  120  can be integrated into driver logic  114 , and, in still other embodiments, high voltage driver  118  and decoder  120  can be eliminated entirely. 
     Computing system  100  can also include host processor  128  for receiving outputs from panel processor  102  and performing actions based on the outputs that can include, but are not limited to, moving an object such as a cursor or pointer, scrolling or panning, adjusting control settings, opening a file or document, viewing a menu, making a selection, executing instructions, operating a peripheral device connected to the host device, answering a telephone call, placing a telephone call, terminating a telephone call, changing the volume or audio settings, storing information related to telephone communications such as addresses, frequently dialed numbers, received calls, missed calls, logging onto a computer or a computer network, permitting authorized individuals access to restricted areas of the computer or computer network, loading a user profile associated with a user&#39;s preferred arrangement of the computer desktop, permitting access to web content, launching a particular program, encrypting or decoding a message, and/or the like. 
     Host processor  128  can also perform additional functions that may not be related to panel processing, and can be coupled to program storage  132  and display device  130  such as a liquid crystal display (LCD) for providing a user interface (UI) to a user of the device. For example, a luminescence shock avoidance algorithm according to embodiments of this invention can be implemented in software or firmware and executed by host processor  128  to selectively limit the brightness level of a display device when the display device is activated in a dark environment to prevent the temporary vision impairment that can occur when display device  130  is activated in a dark environment. 
     In some embodiments of this invention, an ambient light sensor  144  may provide a signal or change in state corresponding to the amount of ambient light present. Ambient light sensor  144  can be a photodiode (e.g. a fast pin diode)  146  or any other device (e.g. a phototransistor or other sensing device) known in the art whose current changes as a function of received ambient light, and can include both an infrared (IR) sensor and a visible light sensor. 
       FIG. 2 a    illustrates exemplary brightness functions of ambient light (in lux (one lumen per square meter)) vs. display device brightness or luminance (in nits (one candela per square meter)) for an exemplary display device according to embodiments of this invention. The brightness functions in  FIG. 2 a    indicate that, for a given ambient light level (the x-axis), the display device will be set to a particular brightness level (the y-axis).  FIG. 2 a    demonstrates that as the ambient light decreases, less light is needed from the display to maintain sufficient visibility, and as the ambient light increases, more light is needed from the display to maintain sufficient visibility. In  FIG. 2 a   , lines  200 ,  202 ,  204 ,  206  and  208  represent a sampling of brightness functions (or various modified brightness functions) of ambient light vs. display device brightness that can be selected by a user using a manual display brightness control setting, although it should be noted that the brightness functions need not be largely linear, but can be non-linear and can even include discrete steps. The brightness functions may be mathematical expressions computed by a processor, or look-up tables stored in memory. In the example of  FIG. 2 a   , line  200  can be the default (neutral) display brightness function, but if the user desires a lower display brightness, the control setting can be adjusted down, either in continuous or discrete steps, until an absolute minimum display brightness function  202  is reached. Note that in the example of  FIG. 2 a   , when function  202  hits a minimum ambient light level  214 , it does not drop below a minimum display brightness level  210 , and thus the display will always be illuminated to some degree, even in absolute darkness. However, it should be understood that minimum levels  210  and  214  are not required. 
     Conversely, if the user desires a higher display brightness, the control setting can be adjusted up, either in continuous or discrete steps, passing through brightness functions  204  and  206 , until an absolute maximum display brightness function  208  is reached. Note that in the example of  FIG. 2 a   , function  208  is maintained at maximum display brightness level  212 . At this setting, there is essentially no longer any sensitivity to ambient light, as the display brightness setting is constant, regardless of the ambient light level. It also be understood that in other embodiments, there may be no manual display brightness control, and only a single brightness function (e.g. default function  200 ) may be employed. 
       FIG. 2 a    also illustrates that when the display device is in a standby, sleep or powered-down mode to save battery power, the display is at a zero brightness level  216 . When the display is automatically activated, such as when a telephone call is received, the display will turn on to the brightness level determined by the ambient light level detected by the ambient light sensor. For example, if the device was in a brightly lit room when a call is received, the display brightness level may jump from point  218  to point  220 . Because the user&#39;s eyes are likely to be already adjusted to the lighting in the room, the sudden change in display brightness level from point  218  to point  220  should not cause any luminescence shock. However, if the device is in a car being driven at night, for example, when a call is received, the display brightness level may jump from point  222  to point  224 . Although the display brightness level of point  224  is far less than point  220 , nevertheless because the user&#39;s eyes are likely to be already adjusted to the darkness of the car, the sudden change in display brightness level from point  222  to point  224  can cause luminescence shock and temporary vision impairment, which can be dangerous to the operator of the car. 
     To avoid luminescence shock, an algorithm may be applied as follows. If the display device is off and a call or other triggering activity is detected, the ambient light sensor will turn on and detect a certain ambient light level. In one embodiment, if the detected ambient light level is greater than or equal to a luminescence shock threshold value  226 , then the display device will turn on at a brightness level according to the current display brightness setting. In other words, if the ambient light level is greater than or equal to threshold value  226 , the display will turn on from a zero brightness level to the level defined by the appropriate brightness function as determined by the current display brightness setting (e.g. from point  218  to point  220 ). Threshold value  226  can be determined empirically and then used as a fixed value in the algorithm, or it can be user programmable. Because threshold value  226  is chosen such that no luminescence shock is expected for ambient light levels above the threshold value, no adjustment is made to the display brightness level when the display turns on. 
     However, if the detected ambient light level is below threshold value  226 , luminescence shock may occur, so the display device will turn on from a zero brightness level to an initially reduced brightness level as compared to what would normally be expected if the brightness function appropriate for the current display brightness level was followed. In other words, the display will initially turn on to a brightness level less than the appropriate brightness function as determined by the current display brightness setting (e.g. from point  222  to point  228 , which is less than point  224 ). This dimmer than usual brightness level is intended to avoid luminescence shock. After some short time period has passed (e.g. five seconds), giving the user&#39;s eyes time to adjust, the brightness level can be gradually or instantly increased to the level determined by the appropriate brightness function (see arrow  230 ), which should be closer to ideal for sufficient visibility at the current ambient light level. 
     In other embodiments, threshold  226  is not used, and therefore regardless of the detected ambient light level, the display will initially turn on to a brightness level less than the appropriate brightness function as determined by the current display brightness setting. Optionally, as above, after some short time period has passed, the brightness level can be gradually or instantly increased to the level determined by the appropriate brightness function. 
     If the display device is already on and a call or other triggering activity is detected, there will be no change to the display brightness, regardless of the current light level. In other words, the luminescence shock avoidance algorithm can be employed only when the display device is initially off. 
     The reduced brightness value may be implemented in a number of different ways.  FIG. 2 b    illustrates one embodiment of this invention wherein if the detected ambient light level is below threshold  226 , the reduced display brightness value may be a fixed value  240 , regardless of the current display brightness settings. After some short time period has passed, the brightness level can be gradually or instantly increased to the level determined by the brightness function appropriate for the current display brightness settings. In the example of  FIG. 2 b   , two brightness functions  200  and  204  are shown representing two different possible current display brightness settings. If the current display brightness settings correspond to brightness function  200 , then the display device turns on to a reduced brightness level  240  (see arrows  232 ), and then after some time has passed, the display device returns to the brightness levels determined by brightness function  200  (see arrows  234 ). Even if the current display brightness settings correspond to brightness function  204 , the display device turns on to the same reduced brightness level  240  (see arrows  236 ), and then after some time has passed, the display device returns to the brightness levels determined by brightness function  204  (see arrows  238 ). 
       FIG. 2 c    illustrates one embodiment of this invention wherein if the detected ambient light level is below threshold  226 , the reduced display brightness value is a fixed value that is dependent on the current display brightness settings. After some short time period has passed, the brightness level can be gradually or instantly increased to the level determined by the brightness function appropriate for the current display brightness settings. In the example of  FIG. 2 c   , two brightness functions  200  and  204  are shown representing two different possible current display brightness settings. If the current display brightness settings correspond to brightness function  200 , then the display device turns on to a reduced brightness level  240  associated with brightness function  200  (see arrows  232 ), and then after some time has passed, the display device returns to the brightness levels determined by brightness function  200  (see arrows  234 ). If the current display brightness settings correspond to brightness function  204 , the display device turns on to a higher reduced brightness level  246  associated with brightness function  204  (see arrows  242 ), and then after some time has passed, the display device returns to the brightness levels determined by brightness function  204  (see arrows  244 ). 
     As the example embodiment of  FIG. 2 c    illustrates, the fixed values  240  and  246  can depend on the current display brightness settings. For example, the higher the current display brightness settings, the higher the fixed value. At the lowest possible current display brightness settings, the fixed value can be the minimum display brightness value  210  (see  FIG. 2 a   ). 
       FIG. 2 d    illustrates one embodiment of this invention wherein if the detected ambient light level is below threshold  226 , the reduced display brightness value is dependent only on the detected ambient light level, regardless of the current display brightness settings. After some short time period has passed, the brightness level can be gradually or instantly increased to the level determined by the brightness function appropriate for the current display brightness settings. In the example of  FIG. 2 d   , two brightness functions  200  and  204  are shown representing two different possible current display brightness settings. If the current display brightness settings correspond to brightness function  200 , then the display device turns on to a reduced brightness level as determined by the detected ambient light level and reduced brightness function  248  (see arrows  250 ). Note that although reduced brightness function  248  is shown in  FIG. 2 d    as a piecewise linear function, any type of function could be used, as long as it represents a reduced brightness level. The reduced brightness function may be a mathematical expression computed by a processor, or may be a look-up table stored in memory. After some time has passed, the display device returns to the brightness levels determined by brightness function  200  (see arrows  252 ). Even if the current display brightness settings correspond to brightness function  204 , the display device turns on to the same reduced brightness level as determined by the detected ambient light level and reduced brightness function  248  (see arrows  254 ), and then after some time has passed, the display device returns to the brightness levels determined by brightness function  204  (see arrows  256 ). 
       FIG. 2 e    illustrates one embodiment of this invention wherein if the detected ambient light level is below threshold  226 , the reduced display brightness value is dependent both on the detected ambient light level and the current display brightness settings. After some short time period has passed, the brightness level can be gradually or instantly increased to the level determined by the brightness function appropriate for the current display brightness settings. In the example of  FIG. 2 e   , two brightness functions  200  and  204  are shown representing two different possible current display brightness settings. If the current display brightness settings correspond to brightness function  200 , then the display device turns on to a reduced brightness level as determined by the detected ambient light level and reduced brightness function  248  associated with brightness function  200  (see arrows  250 ). After some time has passed, the display device returns to the brightness levels determined by brightness function  200  (see arrows  252 ). If the current display brightness settings correspond to brightness function  204 , the display device turns on to a reduced brightness level as determined by the detected ambient light level and reduced brightness function  254  associated with brightness function  204  (see arrows  256 ), and then after some time has passed, the display device returns to the brightness levels determined by brightness function  204  (see arrows  258 ). 
     Even in embodiments without an ambient light sensor, and therefore no detected ambient light level, luminescence shock can be avoided.  FIG. 2 f    illustrates one embodiment of this invention in which when the display device is on, it remains at a constant level  260 , regardless of the ambient light level. In some embodiments, this constant level  260  can be adjusted up or down as indicated by arrows  262  using a manual display brightness control. When a telephone call or other triggering activity is detected, the display may initially come on with a reduced brightness value  264  as compared to line  260  (see arrows  266 ). After some short time period has passed, the brightness level can be gradually or instantly increased to the level determined by brightness level  260  (see arrows  268 ). 
     In some embodiments of this invention, the wavelength of light from the display can be shifted to further reduce luminescence shock.  FIG. 3  is a plot of wavelength vs. pupil sensitivity, showing that the pupils are more sensitive to blue/green light (i.e. the pupils tend to constrict more) as compared to red light. Thus, if ambient light levels below a certain threshold are detected when a telephone call or other activity is detected and the display is turned on, the color of the display can be temporarily gamma-shifted into the red region, either alone or in combination with reduced display brightness levels as described above. By gamma-shifting the display towards red light (see arrow  300 ), the brightness of the display will tend to cause the user&#39;s pupils to constrict less, so that when the user looks up again at a dark road, for example, the user&#39;s vision impairment is reduced. If gamma-shifting is applied in combination with reduced display brightness levels, the display brightness levels may not need to be reduced as much. 
       FIG. 4  is a more detailed view of the host processor, ambient light sensor and display device shown in  FIG. 1 . In  FIG. 4 , host processor  400  receives information on detected ambient light levels from ambient light sensor  402  through an interface which can include and I.sup.2C digital serial interface  404 . Host processor  400  can execute luminescence shock software or firmware  406  and control the brightness of display device  408  using control signals  410 . In addition, gamma-shift logic  412 , which can be a color lookup table, can perform the gamma-shifting described above to alter the RGB inputs to display device  408  and shift the display to the red spectrum as described above. 
       FIG. 5 a    illustrates an exemplary mobile telephone  536  having sensor panel  524  and display device  530  and a processor that can include the luminescence shock avoidance algorithms as described above according to embodiments of this invention.  FIG. 5 b    illustrates an exemplary digital audio/video player  538  having sensor panel  524  and display device  530  and a processor that can include luminescence shock avoidance algorithms as described above according to embodiments of this invention. The mobile telephone and digital audio/video player of  FIGS. 5 a  and 5 b    can advantageously benefit from the luminescence shock avoidance algorithms because they can limit the amount of temporary vision impairment that can occur when a previously dark display device is illuminated in a dark environment, which can be hazardous in certain situations such as when the user is driving a car at night. 
     Although the present invention has been fully described in connection with embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of the present invention as defined by the appended claims.

Metadata:
Filing Date: 20171212
Publication Date: 20190716
Grant Date: 20190716
Priority Date: 20070105
Inventors: PANTFOERDER, KAI ACHIM
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G3/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0606", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0633", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0606", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2330/021", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0653", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/2003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0633", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/2003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0653", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G5/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2330/021", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0606", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G5/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 39593888