Heater for sheet material

#1. Field of the Invention:

#This invention relates generally to heaters. More specifically, the present invention relates to a linear heater which can be advantageously used in an office automation apparatus such as a photocopier or electrophotographic printer for fixing images on a paper sheet for example. The present invention also relates to a heating unit incorporating such a heater.

#2. Description of the Prior Art:

#In the accompanying drawings:

#FIG. 1 is a plan view showing a heater according to a first embodiment of the present invention;

#FIG. 2 is a fragmentary sectional view taken along lines II--II in FIG. 1;

#Preferred embodiments of the present invention are now described with reference to FIGS. 1 through 11 of the accompanying drawings. In these figures, like parts are designated by like reference numerals and characters.

#FIGS. 1-3 show a heater according to a first embodiment of the present invention.

#Referring first to FIGS. 1 and 2, the heater H1 of this embodiment comprises an elongate substrate 1 made of a heat-resistant insulating material such as ceramic. The substrate has a top surface formed with a heating resistor strip 2 extending longitudinally of the substrate. Further, the top surface of the substrate carries a pair of enlarged terminal electrodes 3 electrically connected to the resistor strip 2. A protective glass coating 4 covers the entirety of the resistor strip 2 and part of the respective terminal electrodes 3 (see FIG. 2). The exposed portion of each electrode 3 is used for electrically connecting to a power supply line (not shown).