OLED Driver and Lighting Apparatus Equipped With the Driver
An OLED driver possesses a square-wave voltage source, a controller and a detector. In accordance with first control, the source generates square-wave voltage and applies the voltage across at least one organic electroluminescence element to drive the element. The controller controls the source in accordance with the first control. The detector detects equivalent capacitance inherent in the element. The controller also judges whether or not the element is normal based on the equivalent capacitance. If the element is normal, the controller operates in accordance with the first control. If the element is not normal, the controller operates in accordance with predetermined second control for the element which is not normal.
1 . An OLED driver, comprising:
a square-wave voltage source that generates square-wave voltage and applies the voltage across at least one organic electroluminescence element to drive the element, in accordance with first control; and
a controller that controls the source in accordance with the first control;
wherein: the driver further comprises a detector that detects equivalent capacitance inherent in the element; and
the controller judges whether or not the element is normal based on the equivalent capacitance detected with the detector and then operates in accordance with the first control if the element is normal, while operating in accordance with predetermined second control for the element which is not normal if the element is not normal.
2 . The OLED driver of claim 1 , wherein the detector measures transient current waveform in response to a rise in the voltage applied across the element to detect the equivalent capacitance.
3 . The OLED driver of claim 1 , wherein the detector measures discharge current waveform in response to a fall in the voltage applied across the element to detect the equivalent capacitance.
4 . The OLED driver of claim 2 , wherein the detector detects the equivalent capacitance per period of the square-wave voltage.
5 . The OLED driver of claim 3 , wherein the detector detects the equivalent capacitance per period of the square-wave voltage.
6 . The OLED driver of claim 2 , wherein the detector detects the equivalent capacitance after a predetermined time elapses from a start of the element.
7 . The OLED driver of claim 3 , wherein the detector detects the equivalent capacitance after a predetermined time elapses from a start of the element.
8 . The OLED driver of claim 2 , wherein the detector detects the equivalent capacitance only for a predetermined time from a start of the element.
9 . The OLED driver of claim 3 , wherein the detector detects the equivalent capacitance only for a predetermined time from a start of the element.
10 . The OLED driver of claim 2 , wherein in case of the second control, the controller controls the source so as to lower output voltage of the source.
11 . The OLED driver of claim 3 , wherein in case of the second control, the controller controls the source so as to lower output voltage of the source.
12 . The OLED driver of claim 2 , wherein in case of the second control, the controller controls the source so as to raise output voltage of the source.
13 . The OLED driver of claim 3 , wherein in case of the second control, the controller controls the source so as to raise output voltage of the source.
14 . The OLED driver of claim 2 , wherein in case of the second control, the controller controls the source so as to change output voltage of the source in response to the equivalent capacitance detected with the detector.
15 . The OLED driver of claim 3 , wherein in case of the second control, the controller controls the source so as to change output voltage of the source in response to the equivalent capacitance detected with the detector.
16 . The OLED driver of claim 2 , wherein in case of the second control, the controller controls the source so as to stop the output of the source.
17 . The OLED driver of claim 3 , wherein in case of the second control, the controller controls the source so as to stop the output of the source.
18 . Lighting apparatus, comprising the OLED driver and said at least one organic electroluminescence element of claim 1 .
19 . Lighting apparatus, comprising the OLED driver and said at least one organic electroluminescence element of claim 2 .
20 . Lighting apparatus, comprising the OLED driver and said at least one organic electroluminescence element of claim 3 .