Browse Prior Art Database

EXPOSURE LAMP CONTROL

IP.com Disclosure Number: IPCOM000024818D
Original Publication Date: 1982-Apr-30
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 82K

Publishing Venue

Xerox Disclosure Journal

Abstract

This disclosure relates to a document imaging system and describes a method of controlling exposure variations caused by operating temperature variations of the document illuminating light source. A typical light source in a document copier, such as a fluorescent lamp, has a light output that varies as a function of operating temperature. For example, over a temperature span of 80°F to 120°F, the light output within a single run can vary as much as +/- 20%, respectively.

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XEROX DISCLOSURE JOURNAL

EXPOSURE LAMP CONTROL Proposed Alvin Eng Classification

U.S. CI. 355/8 Int. Cl. G03g 15/28

FIG. I

Volume 7 Number 2 March/April 1982 105

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EXPOSURE LAMP CONTROL (Cont'd)

This disclosure relates to a document imaging system and describes a method of controlling exposure variations caused by operating temperature variations of the document illuminating light source. A typical light source in a document copier, such as a fluorescent lamp, has a light output that varies as a function of operating temperature. For example, over a temperature span of 80°F to 120°F, the light output within a single run can vary as much as +/- 20%, respectively.

Figure 1 illustrates a portion of an illumination system wherein a document lying on a glass platen 10, is to be illuminated by fluorescent lamp 12. Light from the lamp is directed through aperture 14 onto the underside of the platen.

A bi-metallic occluder strip 16 is bonded to the lamp as shown. The edge of strip 16 acts as a light occluder allowing variable amounts of light to pass from the lamp to the platen as a function of lamp temperature. For example, assuming a lamp heater is used, the initial .lamp temperature is at2&1OO0F. As copies of the document are made, the lamp temperature will continue to rise, for example, to 120°F, reducing the lamp output by 20%. However, bi-metallic occluder strip 16 will bend with increased temperatur...