Browse Prior Art Database

Field Disturbance Sensor Auto Level Control

IP.com Disclosure Number: IPCOM000052615D
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Powell, KE: AUTHOR

Abstract

This sensor retains the advantages of that described in [*] and functio better in unstable ambient light conditions due to the inclusion of an additional light sensitive device arranged for adjusting the circuit to the ambient light.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 2

Field Disturbance Sensor Auto Level Control

This sensor retains the advantages of that described in [*] and functio better in unstable ambient light conditions due to the inclusion of an additional light sensitive device arranged for adjusting the circuit to the ambient light.

A lens 10 (Fig. 1) is disposed to encompass a preselected field of view. A tube 12 carries and spaces the lens a distance equal to its focal length f from the active surface of light-dependent resistors (LDRs) 14, 16, 18 supported in a plane normal to the lens axis. LDR 18 is centered while LDRs 14 and 16 are spaced f/4 off center. In this manner LDRs 14 and 16 monitor the left and right hand portions, respectively, of the field of view.

The resistance of each LDR varies inversely with light intensity. Using this principle, circuitry (Fig. 2) is provided to adjust the effective resistance of the LDRs relative to each other to provide a reference condition when the situation in the field is normal. However, the resistance value of LDR 14' or 16' will change if the conditions in its respective monitored field portion change due to motion, smoke, or relocation of objects. The LDR 18' will vary with ambient light changes and will tend to maintain a constant reference.

The LDR 14', a potentiometer 24, the LDR 16' and another potentiometer 26 are connected in a series-parallel circuit between the LDR 18' and a rheostat 28. The resistance of the latter affects the current flowing in the former. The tops of the potentiometers 24 and 26 are individually connected to a pair of comparing circuits 34 and 36.

T...