Control circuit, light source driving device and display apparatus

Patent metadata

Field	Value
Publication number	US-11257442-B2
Application number	US-201916606521-A
Country	US
Kind code	B2
Filing date	Jan 4, 2019
Priority date	Feb 23, 2018
Publication date	Feb 22, 2022
Grant date	Feb 22, 2022

Abstract

The present disclosure provides a control circuit, a light source driving device and a display apparatus. The control circuit comprises a current source circuit configured to generate a current signal having a magnitude positively correlated with a temperature of a region where the control circuit is located; a conversion circuit coupled to the current source circuit and configured to convert the current signal generated by the current source circuit into a voltage signal; and a first comparison circuit coupled to the conversion circuit and configured to output a control signal for controlling brightness of a light source according to the voltage signal received from the conversion circuit, a magnitude of the control signal being negatively correlated with the temperature of the region where the control circuit is located, and the brightness of the light source being positively correlated with the magnitude of the control signal.

First claim

What is claimed is:

1. A control circuit comprising:
a current source circuit, configured to generate a current signal having a magnitude positively correlated with a temperature of a region where the control circuit is located;
a conversion circuit, coupled to the current source circuit and configured to convert the current signal generated by the current source circuit into a voltage signal; and
a first comparison circuit, coupled to the conversion circuit and configured to output a control signal for controlling brightness of a light source according to the voltage signal received from the conversion circuit, a magnitude of the control signal being negatively correlated with the temperature of the region where the control circuit is located, and the brightness of the light source being positively correlated with the magnitude of the control signal,
wherein the first comparison circuit comprises a first input terminal and a second input terminal, and at least one of the first input terminal and the second input terminal is coupled to the conversion circuit and configured to receive the voltage signal from the conversion circuit, and the first comparioson circuit is configured to output the control signal in response to a magnitude of a voltage signal input to the first input terminal being greater than a magnitude of a voltage signal input to the second input terminal, the magnitude of the control signal being negatively correlated with a different between the voltage signals input to the first input terminal and the second input terminal of the first comparison circuit,
the conversion circuit comprises a first conversion sub-circuit coupled to the first input terminal of the first comparison circuit and configured to provide a first voltage signal to the first input terminal of the first comparison circuit, a magnitude of the first voltage signal being positively correlated with a magnitude of the current signal generated by the current source circuit, and
the conversion circuit comprises a second conversion sub-circuit coupled to the second input terminal of the first comparison circuit and configured to provide a second voltage signal to the second input terminal of the first comparison circuit, a magnitude of the second voltage signal being negatively correlated with a magnitude of the current signal generated by the current source circuit.

2. The control circuit of claim 1 , further comprising a second comparison circuit, wherein the second comparison circuit is configured to output a turn-off signal for controlling a display apparatus having the control circuit to be turned off in response to a magnitude of a voltage signal input to a first input terminal of the second comparison circuit being greater than a magnitude of a voltage signal input to a second input terminal of the second comparison circuit, and
the first conversion sub-circuit is further coupled to the first input terminal of the second comparison circuit, and is configured to generate a third voltage signal having a magnitude positively correlated with the magnitude of the current signal generated by the current source circuit and output the third voltage signal to the first input terminal of the second comparison circuit; the magnitude of the third voltage signal is smaller than the magnitude of the first voltage signal.

3. The control circuit of claim 2 , wherein the second conversion sub-circuit is further coupled to the second input terminal of the second comparison circuit and configured to output the second voltage signal to the second input terminal of the second comparison circuit.

4. The control circuit of claim 3 , wherein the second comparison circuit comprises a voltage comparator, a non-inverting input terminal of the voltage comparator is coupled to the first input terminal of the second comparison circuit, an inverting input terminal of the voltage comparator is coupled to the second input terminal of the second comparison circuit, and an output terminal of the voltage comparator is coupled to the output terminal of the second comparison circuit.

5. The control circuit of claim 1 , wherein the current source circuit comprises a current generation circuit configured to generate a bias current signal having a magnitude positively correlated with the temperature of the region where the control circuit is located;
the current source circuit further comprises a first replica circuit coupled to the current generation circuit and the first conversion sub-circuit, and configured to supply a first mirror current signal having a magnitude equal to the magnitude of the bias current signal and output the first mirror current signal to the first conversion sub-circuit; and
the first conversion sub-circuit is configured to convert the first mirror current signal into the first voltage signal.

6. The control circuit of claim 5 , wherein the current source circuit further comprises a second replica circuit coupled to the current generation circuit and the second conversion sub-circuit, and configured to supply a second mirror current signal having a magnitude equal to the magnitude of the bias current signal and output the second mirror current signal to the second conversion sub-circuit; and
the second conversion sub-circuit is configured to convert the second mirror current signal into the second voltage signal.

7. The control circuit of claim 6 , wherein the current generation circuit comprises a first triode, a second triode, a first resistor, a second resistor, a third resistor, a first P-type field effect transistor, a second P-type field effect transistor, a third P-type field effect transistor, a fourth P-type field effect transistor, a first N-type field effect transistor, a second N-type field effect transistor, a third N-type field effect transistor, and a fourth N-type field effect transistor; wherein width-to-length ratios of the first to fourth N-type field effect transistors are the same, and width-to-length ratios of the first to fourth P-type field effect transistors are the same;
a gate electrode of the first P-type field effect transistor is coupled to a second electrode of the second P-type field effect transistor, a first electrode of the first P-type field effect transistor is coupled to a power supply terminal, and a second electrode of the first P-type field effect transistor is coupled to a first electrode of the second P-type field effect transistor;
a gate electrode of the third P-type field effect transistor is coupled to the gate electrode of the first P-type field effect transistor, a first electrode of the third P-type field effect transistor is coupled to the power supply terminal, and a second electrode of the third P-type field effect transistor is coupled to a first electrode of the fourth P-type field effect transistor;
a gate electrode of the fourth P-type field effect transistor is coupled to a gate electrode of the second P-type field effect transistor and a first electrode of the third N-type field effect transistor, and a second electrode of the fourth P-type field effect transistor is coupled to a gate electrode of the third N-type field effect transistor and a gate electrode of the fourth N-type field effect transistor;
a gate electrode of the first N-type field effect transistor is coupled to a gate electrode of the second N-type field effect transistor and a first electrode of the fourth N-type field effect transistor, and a first electrode of the first N-type field effect transistor is coupled to a second electrode of the third N-type field effect transistor;
a first electrode of the second N-type field effect transistor is coupled to a second electrode of the fourth N-type field effect transistor;
a first terminal of the first resistor is coupled to a second e

Assignees

• Fuzhou Boe Optoelectronics Tech Co Ltd
• Boe Technology Group Co Ltd

Inventors

• Hu Ye
• Lu Xiaoying

Classifications

• G09G3/3406 Primary

  Control of illumination source (illumination devices structurally associated with liquid crystal cells G02F1/1336) · CPC title

• G09G2320/064

  by time modulation of the brightness of the illumination source · CPC title

• G05F3/225

  producing a current or voltage as a predetermined function of the temperature · CPC title

• G05F3/30

  Regulators using the difference between the base-emitter voltages of two bipolar transistors operating at different current densities (G05F3/26 takes precedence) · CPC title

• G09G3/36

  using liquid crystals · CPC title