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US 9,805,660 B2Granted
Display device and method for correcting signal voltage using determined threshold voltage shift
AssigneeJoled Inc.
InventorsHiroshi Hayashi, Takahiro Kawashima
Life of this patent
Estimating the term…
Abstract
A display is provided that includes a display having a light-emitting element and a drive transistor, which supplies a current to the light-emitting element causing the light-emitting element to emit light. The display also includes a signal line driving circuit that supplies a signal voltage applied between a gate and a source of the drive transistor, and a control circuit that calculates an amount of threshold voltage shift of the drive transistor on the basis of an amount of deterioration of a threshold voltage of the drive transistor during a deterioration period, and corrects the signal voltage in accordance with the amount of threshold voltage shift.
Claims7
A display device, comprising:
- a display including light-emitting pixels each of which includes a light-emitting element and a drive transistor, the drive transistor including a gate electrode, a source electrode and a drain electrode, and being configured to supply a current to the light-emitting element to cause the light-emitting element to emit light;
- a signal line driving circuit configured to supply a signal voltage applied between the gate electrode and the source electrode of the drive transistor;
- a memory that stores correction data including a representative drive transistor threshold voltage deterioration curve, characteristics of the drive transistor of each light-emitting pixel, and an accumulated stress of the drive transistor of each light-emitting pixel;
- and
- a control circuit configured to
- calculate, using the correction data stored in the memory, an amount of threshold voltage shift of the drive transistor on the basis of an amount of deterioration of a threshold voltage of the drive transistor during a deterioration period in which the signal voltage is kept at a value that is not zero and an amount of recovery of the threshold voltage of the drive transistor during a recovery period in which the signal voltage is kept at zero;
- refer to a representative deterioration curve that shows a relationship between an application time of the signal voltage and the amount of threshold voltage shift in a case where the signal voltage is a predetermined reference voltage;
- store, as an accumulated converted time, a value of the application time that corresponds to the amount of threshold voltage shift on the representative deterioration curve;
- convert a duration of the deterioration period into a converted time that is a time required for deteriorating the threshold voltage of the drive transistor by the amount of deterioration in a case where the signal voltage is the reference voltage;
- calculate the accumulated converted time at an end of the deterioration period by adding the converted time to the accumulated converted time at a start of the deterioration period;
- calculate the amount of threshold voltage shift at the end of the deterioration period by calculating a value of the amount of threshold voltage shift that corresponds to the accumulated converted time at the end of the deterioration period on the representative deterioration curve;
- and
- correct the signal voltage in accordance with the amount of threshold voltage shift.
10 more elements
A display device, comprising:
- a display including light-emitting pixels each of which includes a light-emitting element and a drive transistor, the drive transistor including a gate electrode, a source electrode and a drain electrode, and being configured to supply a current to the light-emitting element to cause the light-emitting element to emit light;
- a signal line driving circuit configured to supply a signal voltage applied between the gate electrode and the source electrode of the drive transistor;
- a memory that stores correction data including a representative drive transistor threshold voltage deterioration curve, characteristics of the drive transistor of each light-emitting pixel, and an accumulated stress of the drive transistor of each light-emitting pixel;
- and
- a control circuit configured to
- calculate, using the correction data stored in the memory, an amount of threshold voltage shift of the drive transistor on the basis of an amount of deterioration of a threshold voltage of the drive transistor during a deterioration period in which the signal voltage is kept at a value that is not zero and an amount of recovery of the threshold voltage of the drive transistor during a recovery period in which the signal voltage is kept at zero;
- calculate the amount of recovery ΔVth_r in accordance with the following equations:
- Δ
-
-
- V
- th
-
-
- _
-
-
- r
- =
- Δ
-
-
- V
- th
-
-
- _
-
-
- ini
-
- exp
-
- {
- -
- (
- t
- r
- τ
- )
- γ
- }
- and
- τ
- =
- τ
- 0
-
- exp
-
- (
- E
- τ
- kT
- )
- where ΔVth_ini is the amount of threshold voltage shift at the start of the recovery period, tr is a duration of the recovery period, τ0 is a coefficient, Eτ is activation energy of a time constant τ of escape of a carrier from a gate insulating film of the drive transistor, k is a Boltzmann constant, T is temperature, and γ is a predetermined constant;
- and
- correct the signal voltage in accordance with the amount of threshold voltage shift.
55 more elements
A method for driving a display device including a display, which includes light-emitting pixels each of which includes a light-emitting element and a drive transistor, the drive transistor including a gate electrode, a source electrode and a drain electrode, and being configured to supply a current to the light-emitting element to cause the light-emitting element to emit light;
- a memory that stores correction data, and a signal line driving circuit configured to supply a signal voltage applied between the gate electrode and the source electrode of the drive transistor, the method comprising:
- accessing the memory that stores the correction data, which includes a representative drive transistor threshold voltage deterioration curve, characteristics of the drive transistor of each light-emitting pixel, and an accumulated stress of the drive transistor of each light-emitting pixel;
- calculating, using the correction data stored in the memory, an amount of threshold voltage shift of the drive transistor on the basis of an amount of deterioration of a threshold voltage of the drive transistor during a deterioration period in which the signal voltage is kept at a value that is not zero and an amount of recovery of the threshold voltage of the drive transistor during a recovery period in which the signal voltage is kept at zero;
- referring to a representative deterioration curve that shows a relationship between an application time of the signal voltage and the amount of threshold voltage shift in a case where the signal voltage is a predetermined reference voltage;
- storing, as an accumulated converted time, a value of the application time that corresponds to the amount of threshold voltage shift on the representative deterioration curve;
- converting a duration of the deterioration period into a converted time that is a time required for deteriorating the threshold voltage of the drive transistor by the amount of deterioration in a case where the signal voltage is the reference voltage;
- calculating the accumulated converted time at an end of the deterioration period by adding the converted time to the accumulated converted time at a start of the deterioration period;
- calculating the amount of threshold voltage shift at the end of the deterioration period by calculating a value of the amount of threshold voltage shift that corresponds to the accumulated converted time at the end of the deterioration period on the representative deterioration curve;
- and
- correcting the signal voltage in accordance with the amount of threshold voltage shift.
7 more elements
Dependencies are inferred from the claim text.