Flicker detecting system for detecting lamp life differing from lamp to lamp

• US 20050156537A1
• Filed: 01/19/2005
• Published: 07/21/2005
• Est. Priority Date: 01/19/2004
• Status: Active Grant

• Current Assignee: NEC Display Solutions, Ltd. (NEC Corporation)
• Original Assignee: NEC Viewtechnology, Ltd.
• Inventors: Kuroda, Atushi
• Granted Patent: US 7,119,492 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H05B 41/2925 against abnormal lamp operating conditions
• CPC Class Codes: H05B 47/24 Circuit arrangements for protecting against overvoltage
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A flicker detection system according to the present invention has an AC component extracting circuit that extracts an AC signal from a voltage applied to a lamp, the AC signal being an AC component of the voltage applied to the lamp, a display section adapted for displaying the information that flicker has occurred, and a control section that has a reference voltage registered in advance for determining that flicker has occurred and instructs the display section to display the information that flicker has occurred in the lamp, depending on the result of comparison between the reference voltage and the AC signal received from the AC component extracting circuit. In the present invention, when flicker occurs in a lamp, the voltage fluctuation generated between the lamp electrodes exceeds the reference voltage, and accordingly, the occurrence of flicker is determined by comparing the AC signal representative of the voltage fluctuation with the reference voltage, and when flicker occurs, a display to that effect is made.

Claims

1. A flicker detection system for detecting flicker that occurs in a lamp, comprising

an AC component extracting circuit that extracts an AC signal from a voltage applied to said lamp, said AC signal being an AC component of said voltage applied to said lamp,

a display section adapted for displaying an information that flicker has occurred in said lamp, and

a control section that has a reference voltage registered in advance for determining an occurrence of flicker and instructs said display section to display the information that flicker has occurred in said lamp, depending on a result of comparison between said reference voltage and said AC signal received from said AC component extracting circuit.

2. A flicker detection system according to claim 1, wherein said control section is provided with a comparison circuit for determining whether or not a voltage amplitude of said AC signal is high in comparison with said reference voltage.

3. A flicker detection system according to claim 1, further provided with a first auxiliary detection circuit that converts a luminescence intensity of said lamp to a voltage value and adds an AC auxiliary signal, which is a signal representative of an AC component of said value of voltage, to said AC signal.

4. A flicker detection system according to claim 1, further provided with a second auxiliary detection circuit that converts a luminescence intensity of said lamp to a voltage value and sends a DC auxiliary signal, which is a signal representative of a DC component of said voltage value, to said control section, wherein

said control section has reference intensity data registered in advance, compares said DC auxiliary signal, received from said second auxiliary detection circuit, with said reference intensity data, and instructs said display section to display the information that flicker has occurred in said lamp if said DC auxiliary signal has a level lower than said reference intensity data and also if a voltage amplitude of said AC signal is higher than said reference voltage.

5. A projector apparatus provided with the flicker detection system according to claim 1.

6. A method of detecting flicker through a use of a flicker detection system having a display section, comprising:

a step of registering a reference voltage for determining on flicker,

a step of extracting an AC signal that is a signal representing an AC component of a voltage applied to a lamp, and

a step of instructing said display section to display an information that flicker has occurred in said lamp, depending on a result of comparison of said AC signal with said reference voltage.