Mechanism and method for controlling the temperature and output of a fluorescent lamp

• US 4,533,854 A
• Filed: 03/25/1983
• Issued: 08/06/1985
• Est. Priority Date: 03/25/1983
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Northrup, Karl A.
• Primary Examiner(s): Chatmon, Saxfield
• Application Number:
  US06/478,746
• Time in Patent Office: 865 Days
• Field of Search: 315/112, 315/113, 315/114, 315/115, 315/116, 315/117, 315/149, 315/150, 315/158, 250/205
• US Class Current: 315/117
• CPC Class Codes: H01J 61/52 Cooling arrangements; Heating arrangements; Means for circulating gas or vapour within the discharge space heating or cooling arrangements to promote ionisation for starting H01J61/54
• CPC Class Codes: H05B 41/00 Circuit arrangements or apparatus for igniting or operating discharge lamps structurally associated with the discharge lamps H01J61/54, H01J61/56

Abstract

The light output of a fluorescent lamp is controlled and optimized. The light output of a lamp peaks at some optimum value of mercury cold spot temperature. During operation the lamp output is continually monitored, any drop in peak light output is detected, and a signal is generated which reverses the instant mode of operation of a cooling device placed in proximity to the lamp cold spot. With the cooling mode reversed, the light output will rise towards the peak. The cooling mode remains unaltered until the light output falls again.

Claims

1. A monitoring and control mechanism for optimizing and controlling the light output of a fluorescent lamp containing an excess of mercury at a cold spot therein, said mechanism comprising:

a power supply for applying a constant operating current to said lamp,

a monitoring means for detecting a drop in a light output of said lamp and for generating a signal indicative thereof,

a temperature control device placed in proximity to said cold spot, said device, when operational, serving to provide a constant intensity output to lower the temperature of the cold spot and, when non-operational, effectively permitting the cold spot temperature to rise,

a controller circuit adapted to change the operational state of said temperature control device in response to the output signals from said monitoring means.

2. The mechanism of claim 1 wherein said controller circuit is adapted to analyze the direction of light decrease and to send a signal to said temperature control device so as to reverse its state of operation.

3. The mechanism of claim 1 wherein said monitoring means is a photodetector.

4. A method of optimizing the light output of a fluorescent lamp containing an excess of mercury at a cold spot thereon comprising the steps of:

monitoring the light output of said lamp,

modifying the temperature at said cold spot by means of a temperature regulating device having an active mode of operation serving to provide a constant intensity output and an inactive mode of operation, and

generating an electrical signal responsive to a dropoff from the optimum light output level, causing the instant mode of operation of said temperature regulating to be changed in response to said energy level.