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US 6,421,034 B1Granted
EL driver circuit
AssigneeSTMicroelectronics S.r.l.
InventorMasaaki Mihara
Life of this patent
Estimating the term…
Abstract
A serial resonant circuit, formed by EL panel (CEL) and coil (L1), is connected to a push-pull driver through a positive feedback path to form an oscillator circuit. The EL panel is driven by a sinusoidal driving signal to emit light. The voltage level of the EL panel driving signal is adjusted corresponding to the change in the capacitance of the EL panel so that the luminous brightness of the EL panel can be maintained on a constant level.
Claims27
An EL driver circuit, comprising:
- a push-pull driver having an output end and an input end and is coupled between a supply voltage and a first fixed voltage,
- an EL panel that can effectively form a capacitor, and a coil which is connected in series to the EL panel;
- one end of the serial connection of the EL panel and coil is coupled to the output end of the push-pull driver, while the other end is coupled to the input end of the push-pull driver in a positive feedback manner;
- a voltage level detecting circuit to detect a change in a driving voltage of the EL panel based on a reference voltage and an integrated voltage of the driving voltage and to generate a detection signal for adjusting the supply voltage to the EL panel.
1 more element
An EL driver circuit comprising:
- a push-pull driver coupled between a supply voltage and a first fixed voltage and configured to output the supply voltage in the form of a rectangular wave;
- a coil coupled to an EL panel to constitute a resonant circuit, and which is connected in a loop formed by closing the push-pull driver and the resonant circuit;
- an integrator circuit configured to integrate the driving voltage of the EL panel and generate an integrated voltage;
- a driving voltage level detecting circuit configured to detect the change in the level of the driving voltage of the EL panel based on the first reference voltage and the integrated voltage obtained from the integrator circuit;
- a supply voltage level adjusting circuit configured to generate an adjustment signal to adjust the level of the supply voltage supplied to the push-pull driver corresponding to a detection signal sent from the driving voltage level detecting circuit;
- and
- a variable voltage source configured to supply an adjusted supply voltage to the push-pull driver corresponding to the adjustment signal.
4 more elements
A driver circuit for a display panel, the display panel having first and second terminals, the driver circuit comprising:
- a coil having a first terminal coupled to the first terminal on the display panel, and a second terminal;
- a driver having a first voltage source terminal coupled to a voltage source, an output terminal coupled to the second terminal on the coil, and a feedback terminal in communication with the second terminal of the display panel;
- an integrator circuit having an input terminal coupled to the feedback terminal of the push-pull driver, and an output terminal;
- a voltage level detecting circuit having an input terminal coupled to the output terminal of the integrator circuit, and an output terminal;
- a supply voltage level adjusting circuit having an input terminal coupled to the output terminal of the voltage level detecting circuit, and an output terminal;
- and
- a variable voltage source circuit having an input terminal coupled to the output terminal of the supply voltage level adjusting circuit, and an output terminal coupled to the first voltage source terminal on the driver.
4 more elements
A method for driving a display panel, comprising:
- applying a sinusoidal driving signal to the display panel via a push-pull driver that is coupled to the display panel and a coil to form a resonant circuit;
- generating a driving signal pulse array that is also fed back to the push-pull driver;
- integrating the driving signal pulse array to generate an integrated signal at an integrator circuit;
- generating a detection signal at a driving voltage level detecting circuit and generating an adjustment signal at a supply voltage adjustment circuit from a comparison of the integrated signal to a supply voltage used to generate the sinusoidal driving signal;
- and
- applying the adjustment signal to adjust the sinusoidal driving signal.
3 more elements
Dependencies are inferred from the claim text.