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Liquid Ceramic Level Control for Doctor Blade Hopper

IP.com Disclosure Number: IPCOM000087714D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Gardner, DG: AUTHOR [+3]

Abstract

In forming ceramic green sheets, a liquid ceramic material is doctor bladed on a continuously moving belt and subsequently dried. Due to the volatile materials in the liquid ceramic material, it is desirable that the doctor-blade hopper be enclosed. In order to prevent an overflow or depletion of ceramic slurry in the hopper, it is necessary that a level sensing means be provided in the hopper. The conventional float controls are unsuitable since they present hazardous, as well as cleaning problems.

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Liquid Ceramic Level Control for Doctor Blade Hopper

In forming ceramic green sheets, a liquid ceramic material is doctor bladed on a continuously moving belt and subsequently dried. Due to the volatile materials in the liquid ceramic material, it is desirable that the doctor-blade hopper be enclosed. In order to prevent an overflow or depletion of ceramic slurry in the hopper, it is necessary that a level sensing means be provided in the hopper. The conventional float controls are unsuitable since they present hazardous, as well as cleaning problems.

In this ceramic level control, a light-emitting diode and photo-diode combination is utilized to detect the liquid level. A light beam is generated by the light-emitting diode which is directed to the liquid level surface at an angle. The reflected light beam is detected by the photodiode. The relative positions of the light-emitting diode and photodiode are such that when the liquid level is at the desired level, the reflected beam is sensed by the photodiode. When the liquid level drops, there is a loss of the light signal to the photodiode and, therefore, a corresponding loss of the input signal to the associated electronic control package. This loss of signal is utilized to permit a flow which re-supplies ceramic liquid material to the hopper until the level is reached. This will create an output from the photodiode and thereby terminates the supply of liquid material.

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