Lamp driving circuit

Patent metadata

Field	Value
Publication number	US-10212774-B2
Application number	US-201715673889-A
Country	US
Kind code	B2
Filing date	Aug 10, 2017
Priority date	Aug 11, 2016
Publication date	Feb 19, 2019
Grant date	Feb 19, 2019

Abstract

A lamp driving circuit for driving a lamp part, includes a correction part configured to receive a first control signal for driving the lamp part with a predetermined brightness, to receive duty information indicative of a ratio of a supply voltage for operating the lamp part and a voltage across the lamp part, and to correct the first control signal based on the duty information to generate a second control signal, and a control part configured to receive the second control signal from the correction part, and to drive the lamp part with the predetermined brightness based on the second control signal.

First claim

What is claimed is:

1. A lamp driving circuit for driving a lamp part, comprising:
a signal correction circuit configured to receive a first control signal for driving the lamp part with a predetermined brightness, to receive duty information indicative of a ratio of a supply voltage for operating the lamp part and a voltage across the lamp part, and to correct the first control signal based on the duty information to generate a second control signal; and
a controller configured to receive the second control signal from the signal correction circuit, and to drive the lamp part with the predetermined brightness based on the second control signal,
wherein the signal correction circuit is configured to further correct the first control signal based on the second control signal which is input to the controller, and information indicative of brightness of the lamp part corresponding to the second control signal to generate the second control signal,
wherein the signal correction circuit is configured to further correct the first control signal such that a first error in brightness of the lamp part, which occurs due to an internal delay of the controller, is corrected,
wherein the signal correction circuit includes:
first to third resistors configured to correct the first error in brightness of the lamp part which occurs due to the internal delay of the controller; and
a fourth resistor configured to correct a second error in brightness of the lamp part which occurs due to a change in the ratio of the supply voltage for operating the lamp part and the voltage across the lamp part,
wherein the first control signal is applied to one end of the first resistor,
wherein the other end of the first resistor is connected to one of the ends of the second to fourth resistors,
wherein the other end of the second resistor is connected to a DC voltage source,
wherein the other end of the third resistor is connected to a ground, and
wherein the duty information is applied to the other end of the fourth resistor.

2. The circuit of claim 1 ,
wherein the signal correction circuit is configured to correct the first control signal based on the duty information such that the second error in brightness of the lamp part, which occurs due to the change in the ratio of the supply voltage for operating the lamp part and the voltage across the lamp part, is corrected.

3. The circuit of claim 1 , wherein the internal delay of the controller is a delay from a timing when the controller detects that a current flowing through the lamp part has reached a target value to a timing when the current flowing through the lamp part starts to decrease.

4. The circuit of claim 1 , further comprising a signal detection circuit configured to detect a current flowing through the lamp part,
wherein the signal detection circuit is configured to provide a first detection signal to the controller when the current flowing through the lamp part has a first value, and to provide a second detection signal to the controller when the current flowing through the lamp part has a second value greater than the first value, and
the first value is determined based on the second control signal.

5. The circuit of claim 4 , wherein the controller is further configured to decrease the current flowing through the lamp part upon receiving the first detection signal from the signal detection circuit.

6. The circuit of claim 5 , wherein the internal delay of the controller is a delay from a timing when the controller receives the first detection signal to a timing when the current flowing through the lamp part starts to decrease.

7. The circuit of claim 4 , wherein the controller is further configured to increase the current flowing through the lamp part upon receiving the second detection signal from the signal detection circuit.

Assignees

• Rohm Co Ltd

Inventors

• In Jung-Nam
• Kim Jong-Won

Classifications

• H05B45/3725

  Switched mode power supply [SMPS] · CPC title

• H05B45/10 Primary

  Controlling the intensity of the light · CPC title

• H05B33/0815

  Electricity · mapped topic

• H05B33/0851 Primary

  Electricity · mapped topic

• G09G2320/0233

  Improving the luminance or brightness uniformity across the screen · CPC title