Display device
View Patent ↗A display device according to an embodiment of the invention includes a display panel, a drive circuit that drives the display panel, an illuminating unit that illuminates the display panel, a photosensing section Ls having an ambient light photosensor Ts that senses the brightness of ambient light and a capacitor Cw that is charged with a predetermined reference voltage via a first switch S 1 , an ambient light photosensor reading section Re 1 that reads a value sensed by the photosensing section, and a controller that controls the illuminating unit according to an output of the ambient light photosensor reading section. The ambient light photosensor reading section is provided with a noise avoidance unit that avoids erroneous sensing in the photosensing section induced as a result of noise generated when the drive circuit operates. Thanks to such structure, a display device is provided in which sensing of ambient light is free from the effects of noise arising from the parasitic capacitance formed between the electrodes and wiring of the ambient light photosensor and the display panel.
1. A display device comprising:
a display panel;
a drive circuit that drives the display panel;
an illuminating unit that illuminates the display panel;
a photosensing section that is incorporated into the display panel and has an ambient light photosensor that senses the brightness of ambient light and a capacitor that is charged with a predetermined reference voltage via a first switch,
an ambient light photosensor reading section that reads a value sensed by the photosensing section, and
a controller that controls the illuminating unit according to an output of the ambient light photosensor reading section;
the ambient light photosensor reading section being provided with a noise avoidance unit that avoids erroneous sensing in the photosensing section induced as a result of noise generated when the drive circuits operate.
2. The display device according to claim 1 , wherein the noise avoidance unit includes a second switch that connects the photosensing section to the ambient light photosensor reading section, and a switch controller that controls the second switch, and the switch controller performs control so that the second switch is turned on when the drive circuit is generating no noise.
3. The display device according to claim 2 , wherein a low level signal and a high level signal are applied alternately in a predetermined cycle to an electrode of the display panel, and the switch controller performs control so that when the low level signal is applied, the first switch is turned on and, if the capacitor is charged to the reference voltage, the second switch is turned on during application of the low level signal; and when the high level signal is applied, the first switch is turned on and, if the capacitor is charged to the reference voltage, the second switch is turned on during application of the high level signal.
4. A display device comprising:
a display panel;
a drive circuit that drives the display panel;
an illuminating unit that illuminates the display panel;
a photosensing section that is incorporated into the display panel and has an ambient light photosensor that senses the brightness of ambient light and a capacitor that is charged with a predetermined reference voltage via a first switch,
an ambient light photosensor reading section that reads a value sensed by the photosensing section, and
a controller that controls the illuminating unit according to an output of the ambient light photosensor reading section;
the ambient light photosensor reading section including a first comparative circuit that compares the photosensing section's output with a predetermined reference value and outputs a predetermined digital signal, and a noise canceling circuit that receives the digital signal from the first comparative circuit and, if such digital signal varies in a time period shorter than a predetermined time period, judges such digital signal to be noise and excludes such digital signal.
5. The display device according to claim 4 , wherein the noise canceling circuit is provided with a delaying circuit that delays by a predetermined time period the digital signal from the first comparative circuit, and with a second comparative circuit that compares the delayed digital signal from the delaying circuit with the undelayed digital signal from the first comparative circuit, and the second comparative circuit produces output when the delayed and undelayed digital signals coincide.
6. The display device according to claim 4 , wherein the noise canceling circuit includes an enabling circuit that generates an enabling signal when the drive circuit is generating no noise, and the noise canceling circuit produces output while detecting such enabling signal.
7. A display device comprising:
a display panel;
a drive circuit that drives the display panel;
an illuminating unit that illuminates the display panel;
a photosensing section that is incorporated into the display panel and has an ambient light photosensor that senses the brightness of ambient light and a capacitor that is charged with a predetermined reference voltage via a first switch,
an ambient light photosensor reading section that reads a value sensed by the photosensing section, and
a controller that controls the illuminating unit according to an output of the ambient light photosensor reading section;
the ambient light photosensor reading section being provided with a capacitor having the same capacitance as a parasitic capacitance formed between an output wire of the photosensing section and an electrode of the display panel, and a signal of opposite phase to a signal applied to the electrode being applied to the capacitor.