Reliable lamp life timer

• US 20020005697A1
• Filed: 12/21/2000
• Published: 01/17/2002
• Est. Priority Date: 12/28/1999
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Smith, Thomas E., Morgan, Daniel J.
• Granted Patent: US 6,373,201 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H05B 47/20 Responsive to malfunctions or to light source life; for protection

Abstract

A method and apparatus for controlling a lamp. A timer controller (106) reads a rated safe life value from a memory (102) associated with a lamp in a lamp module (104). The memory (102) in the lamp module (104) contains a series of locations in which the rated safe life of the lamp has been stored, and a series of locations for storing the elapsed on time of the lamp. The timer controller (106) reads the series of locations storing the rated safe life of the lamp and verifies the validity of the values using a series of checksums and comparisons between the various values. The timer controller (106) also reads the series of locations storing the elapsed on time for the lamp and verifies the elapsed on time in a similar manner. If either the rated safe on time or the elapsed on time cannot be verified, the lamp is disabled. If both can be verified, and the lamp is enabled until the elapsed on time equals or exceeds the rated safe life.

Claims

1. A method of tracking the elapsed operating time of a light source, the method comprising the steps of:

associating a memory device with a lamp, said memory having a rated safe life value stored therein;

igniting said lamp;

updating an elapsed lamp on time value stored in said memory;

comparing said elapsed lamp on time to said rated lamp life value;

repeating said updating and comparing steps until said elapsed lamp on time exceeds said rated safe life value; and

disabling said lamp when said elapsed lamp on time exceeds said rated safe life value.

2. The method of claim 1, said rated safe life value stored in multiple locations of said memory device, further comprising the steps of:

comparing said multiple locations; and

rewriting inaccurate locations.

3. The method of claim 1, said elapsed lamp on time value stored in multiple locations of said memory device, further comprising the steps of:

comparing said multiple locations; and

rewriting inaccurate locations.

4. The method of claim 1, said memory device logically divided into at least two blocks, further comprising the step of:

verifying a checksum associated with one of said blocks.

5. The method of claim 1, said method further comprising the step of write protecting a group of locations in said memory after writing said rated safe life value therein.

6. The method of claim 1, said method further comprising the steps of:

reading a potentially corrupt rated safe life value from all locations where said rated safe life value is stored; and

setting said rated safe life value equal to the most common potentially corrupt rated safe life value read.

7. The method of claim 1, said method further comprising the steps of:

reading a potentially corrupt rated safe life value from all locations where said rated safe life value is stored; and

disabling said lamp if at least a predetermined percentage of said potentially corrupt rated safe life values are not equal.

8. The method of claim 1, said method further comprising the steps of:

reading a potentially corrupt elapsed lamp on time value from all locations where said elapsed lamp on time value is stored; and

disabling said lamp if at least a predetermined percentage of said potentially corrupt elapsed lamp on time values are not equal.

9. The method of claim 1, said method further comprising the steps of:

reading a potentially corrupt elapsed lamp on value from all locations where said elapsed lamp on time value is stored; and

disabling said lamp if at least a predetermined percentage of said potentially corrupt elapsed lamp on time values are not equal.

10. A display system comprising:

a lamp for generating a beam of light along a light path, said lamp having a rated safe life value;

a memory device associated with said lamp, said rated safe life value stored in said memory;

a timer controller circuit, said timer controller circuit capable of reading said rated safe life value from said memory and storing an elapsed lamp on time value in said memory, said timer controller circuit disabling said lamp when said elapsed lamp on time value exceeds said rated safe life value, and disabling said lamp when either said elapsed lamp on time value or said rated safe life value become irretrievably corrupted;

a spatial light modulator on said light path for modulating said beam of light to produce a modulated beam of light; and

projection optics to focus said modulated beam of light on an image plane.