Pixel circuit, display device, and method for controlling a pixel circuit

Abstract

To provide a pixel circuit, a display device, and a control method for the pixel circuit that can accurately emit light from light-emitting elements. [Solution] The pixel circuit according to this disclosure comprises a current source circuit that generates a first current, a slope signal generation circuit that generates a slope signal whose potential changes linearly using a second current proportional to the first current, and a PWM (Pulse Width Modulation) drive circuit that supplies the first current to the light-emitting element for a period of time corresponding to the result of comparing the slope signal and the video signal.

Claims

1. A current source circuit that generates the first current, A slope signal generation circuit that generates a slope signal in which the potential changes linearly using a second current proportional to the first current, A PWM (Pulse Width Modulation) drive circuit supplies the first current to the light-emitting element for a period of time corresponding to the result of comparing the slope signal and the video signal, A pixel circuit equipped with this feature.

2. The current source circuit is The device has a first transistor of a first conductivity type, which is provided between a light-emitting element and a reference potential terminal to which a reference potential is supplied, and through which the first current corresponding to the potential of the control signal flows. The slope signal generation circuit is, A second transistor of a first conductivity type is provided between the node indicating the potential of the slope signal and the reference potential terminal, and is connected to the first transistor via a current mirror so that a second current proportional to the first current flows through it. A capacitive element is provided between the node and the initial potential terminal to which the initial potential of the slope signal is supplied, A selection circuit that switches between connecting the initial potential terminal and the node, or connecting the node and the reference potential via the second transistor, Having, The pixel circuit according to claim 1.

3. The current source circuit is The first transistor of a first conductivity type is provided between the light-emitting element and a reference potential terminal to which a reference potential is supplied, and through which the first current flows. The slope signal generation circuit is, A second transistor of a first conductivity type is provided between the node indicating the potential of the slope signal and the reference potential terminal, through which the second current flows. A capacitive element is provided between the node and the initial potential terminal to which the initial potential of the slope signal is supplied, A selection circuit that switches between connecting the initial potential terminal and the node, or connecting the node and the reference potential via the second transistor, A third transistor of a second conductivity type is provided between the initial potential terminal and the reference potential terminal, and a current corresponding to the potential of the control signal flows through it. A fourth transistor of the first conductivity type through which the current flowing through the third transistor flows, It has, The first transistor and the second transistor are currently mirrored to the fourth transistor. The pixel circuit according to claim 2.

4. The current source circuit is The device has a first transistor of a first conductivity type, which is provided between a light-emitting element and a reference potential terminal to which a reference potential is supplied, and through which the first current corresponding to the potential of the control signal flows. The slope signal generation circuit is, A second transistor of a first conductivity type is provided between a power supply potential terminal to which a power supply potential is supplied and the reference potential terminal, and is connected to the first transistor via a current mirror so that an intermediate current proportional to the first current flows through it. A third transistor of second conductivity type through which the intermediate current flowing through the second transistor flows, A fourth transistor of second conductivity type is provided between the power supply potential terminal and the node indicating the potential of the slope signal, and is connected to the third transistor via a current mirror so that the second current, which is proportional to the intermediate current, flows through it. A capacitive element is provided between the node and the initial potential terminal to which the initial potential of the slope signal is supplied, A selection circuit that switches between connecting the initial potential terminal and the node, or connecting the power supply potential and the node via the fourth transistor, Having, The pixel circuit according to claim 1.

5. The current source circuit is The first transistor of a first conductivity type is provided between the light-emitting element and a reference potential terminal to which a reference potential is supplied, and through which the first current flows. The slope signal generation circuit is, A second transistor of a second conductivity type is provided between a power potential terminal to which the power potential is supplied and a node indicating the potential of the slope signal, and through which the second current corresponding to the potential of the control signal flows, A capacitive element is provided between the node and the initial potential terminal to which the initial potential of the slope signal is supplied, A selection circuit that switches between connecting the initial potential terminal and the node, or connecting the power supply potential and the node via the second transistor, A third transistor of second conductivity type is provided between the power supply potential terminal and the reference potential terminal, and is connected to the second transistor via a current mirror so that an intermediate current proportional to the second current flows through it. A fourth transistor of the first conductivity type through which the intermediate current flowing through the third transistor flows, Yes, The first transistor is currently mirrored to the fourth transistor. The pixel circuit according to claim 1.

6. The PWM drive circuit is, A comparator compares the aforementioned slope signal and video signal and outputs a PWM signal with a pulse width corresponding to the comparison result. A first switch element is provided between the light-emitting element and the current source circuit, and turns on for a period of time corresponding to the pulse width of the PWM signal. Having, The pixel circuit according to claim 1.

7. The PWM drive circuit is, A comparator compares the aforementioned slope signal and video signal and outputs a PWM signal with a pulse width corresponding to the comparison result. A first switch element that selects and outputs either a control signal to stop the generation of the first current or a control signal to generate the first current to the current source circuit, in accordance with the PWM signal, Having, The pixel circuit according to claim 1.

8. A current source circuit that generates the first current, A slope signal generation circuit that generates a slope signal in which the potential changes linearly using a second current proportional to the first current, Multiple PWM (Pulse Width Modulation) drive circuits supply the first current to each of the multiple light-emitting elements for a period of time corresponding to the result of comparing the slope signal and the video signal, A pixel circuit equipped with this feature.

9. The current source circuit generates the first current with a value corresponding to a control signal supplied from an external source. The pixel circuit according to claim 1.

10. The slope signal generation circuit repeats the linear change of the slope signal from its initial potential two or more times for each input of the video signal. The pixel circuit according to claim 1.

11. One or more light-emitting elements, A pixel circuit according to any one of claims 1 to 10 for driving the light-emitting element, A display device equipped with the following features.

12. The current source circuit generates the first current, The slope signal generation circuit generates a slope signal whose potential changes linearly using a second current that is proportional to the first current. The PWM (Pulse Width Modulation) drive circuit supplies the first current to the light-emitting element for a period of time corresponding to the result of comparing the slope signal and the video signal. A method for controlling pixel circuits.

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