Apple Invents Solar Cell Ambient Light Sensors for iDevices
On June 5, 2014, the US Patent & Trademark Office published a patent application from Apple that reveals ongoing work on solar cell technology. In Apple's latest invention they advance display technology that integrates solar cell ambient light sensors that may one day work with an iPhone, iPad, iWatch, a Mac, television or a vehicle.
Apple's Patent Background
Electronic devices such as smartphones and include displays for presenting information to a user and often include light sensors. For example, an electronic device may include an ambient light sensor that senses the amount of light in the environment surrounding the device. The brightness of display images generated by the display is sometimes adjusted based on the amount of ambient light. For example, in bright sunlight, the display brightness may be increased and in a dark room, the display brightness can be decreased.
In a typical device, a light sensor that is formed from a chip package having a photodiode is laterally displaced from an active display region of the display along a front face of the device. Additional space is therefore provided in common devices at the top, bottom, or side of the active display area to accommodate the light sensor.
This type of additional space for a common light sensor package can result in an undesirable increase in the size and thickness of the device. It would therefore be desirable to be able to provide improved electronic devices with light sensors and displays.
Apple's Invention Covers Solar Cell Ambient Light Sensors for Electronic Devices
An electronic device is provided with a display such as an organic light-emitting diode (OLED) display mounted in an electronic device housing. The electronic device is also provided with one or more light sensors.
The display includes multiple display layers such as one or more light-generating layers, a touch-sensitive layer, and a cover layer. The cover layer may, for example, be a layer of rigid transparent material such as glass or transparent plastic.
The light sensor is formed from one or more solar cells such as a thin-film photovoltaic solar cell. The thin-film solar cell light sensor is configured as a solar cell ambient light sensor that is coupled to circuitry in the device.
The illustrative configurations for device 10 that are shown in Apple's patent FIGS. 1, 2, 3, and 4 above are merely illustrative. In general, the electronic device may be a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment.
Apple further notes that the circuitry includes a printed circuit board and, if desired, additional control circuitry for operating device components such as the display and the solar cell ambient light sensor.
During operation, a voltage is generated on the thin film solar cells in response to ambient light that falls on the thin film solar cells. The voltage is read (sampled) by the control circuitry and an ambient light intensity is determined based on the sampled voltage.
The solar cell ambient light sensor is mounted to a layer of the display such as a display cover layer, a display color filter layer, or an innermost layer of the display. In one suitable example, the solar cell ambient light sensor is mounted to an innermost layer of the display and receives the ambient light through substantially all of the layers of the display.
In configurations in which the solar cell ambient light sensor is mounted to a display cover layer or a display color filter layer, the solar cell ambient light sensor may receive light through a partially opaque masking layer that is formed on the cover layer or the color filter layer. The partially opaque masking layer may block a portion of the light that falls on the masking layer and may transmit another portion of the light. As examples, the partially opaque masking layer may block a fraction of all wavelengths of light or may block some wavelengths of light while passing other wavelengths of light.
The device may be provided with multiple solar cell ambient light sensors. Each solar cell ambient light sensor may receive light having a common set of wavelengths or some solar cell ambient light sensors may be configured to detect light having a first range of wavelengths and other solar cell ambient light sensors may be configured to detect light having a different range of wavelengths. The circuitry may adjust the brightness of the display based on the detected light from the solar cell ambient light sensors.
Apple's patent FIG. 6 is a cross-sectional side view of a portion of an illustrative electronic device having a solar cell ambient light sensor mounted behind at least a portion of a display.
Apple's patent FIG. 15 is a cross-sectional view of a portion of an illustrative electronic device having a solar cell ambient light sensor attached to a display layer that is coated with masking materials.
Apple also notes that displays for device 10 may, in general, include image pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrowetting pixels, electrophoretic pixels, liquid crystal display (LCD) components, or other suitable image pixel structures.
Apple credits Anna-Katrina Shedletsky, Erik Jong, Fletcher Rothkopf and Anthony Montevirgen as the inventors of patent application 20140152632 which was originally filed in Q4 2012. To review the finer details of this invention, see Apple's patent application. Considering that this is a patent application, the timing of such a product to market is unknown at this time.
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