Gate-on voltage generator, driving device and display apparatus comprising the same
View Patent ↗A gate-on voltage generator that can enhance display quality at low temperatures, a driving device, and a display apparatus having the same, in which the gate-on voltage generator includes a temperature sensor having an operational amplifier configured to receive a driving voltage and produce a temperature-dependent variable voltage, the level of which varies according to the ambient temperature, and a charge pumping unit shifting the temperature-dependent variable voltage by the voltage level of a pulse signal and generating a gate-on voltage.
1. A gate-on voltage generator comprising:
a temperature sensor including an operational amplifier configured to receive a driving voltage and produce a temperature-dependent variable voltage, the level of which varies according to an ambient temperature; and
a charge pumping unit shifting the temperature-dependent variable voltage by an amplitude of a pulse signal fed thereto and generating a gate-on voltage,
wherein the temperature sensor comprises one or more diodes each of the one or more diodes having an inherent variable threshold voltage characteristic of the respective diode that varies according to a change of the ambient temperature and produces a variable comparison voltage based upon the variation of the inherent variable threshold voltage characteristic of the one or more diodes, the voltage comparison voltage being fed to an input of the operational amplifier,
wherein the pulse signal fed to the charge pumping unit is a pulse width modulation signal, and
wherein the driving voltage and an amplitude of the pulse signal are irrelevant to an ambient temperature.
2. The gate-on voltage generator of claim 1 , wherein the voltage level of the temperature-dependent variable voltage increases when the ambient temperature falls, and the voltage level of the temperature-dependent variable voltage decreases when the ambient temperature rises.
3. The gate-on voltage generator of claim 2 , wherein the operational amplifier increases a change of the temperature-dependent variable voltage according to the change of the ambient temperature as represented by the comparison voltage.
4. The gate-on voltage generator of claim 2 , wherein the temperature sensor comprises:
a comparison voltage generator including one or more diodes each having a variable threshold voltage according to a change of the ambient temperature and generating a comparison voltage having a variable voltage level according to the ambient temperature; and
an amplifier, including the operational, amplifier, amplifying a difference between the comparison voltage and the reference voltage.
5. The gate-on voltage generator of claim 4 , wherein the comparison voltage generator further includes a fixed resistor connected between a first node and a second node and the diodes that are connected in series between the second node and a third node, and wherein a positive voltage is applied to the first node, the comparison voltage is output via the second node, and a ground voltage is applied to the third node.
6. The gate-on voltage generator of claim 4 , wherein the comparison voltage generator further includes a fixed resistor connected between a first node and a second node and the diodes that are connected in series between the second node and a third node, wherein a positive voltage is applied to the first node, the comparison voltage is output via the second node, and a negative voltage is applied to the third node.
7. The gate-on voltage generator of claim 4 , wherein the temperature sensor further comprises a buffer that provides the amplifier with the comparison voltage without alteration.
8. The gate-on voltage generator of claim 1 , wherein the driving voltage and the amplitude of the pulse signal are not influenced by the ambient temperature.