Browse Prior Art Database

Self-Adjusting Analog Toner Patch Sensor

IP.com Disclosure Number: IPCOM000038731D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Champion, JR: AUTHOR [+2]

Abstract

In a xerographic toner concentration sensor of the patch sensor type, a reference voltage defines the magnitude of the reflected light signal which should be received when the photocell views the bare photoconductor patch. Energization of the light source is controlled to make this reflected light signal equal in magnitude to this reference voltage. In this way, the light reflected from the photoconductor's toned patch is compared to an accurate reference reflectance, during the process of determining the need to add toner. The analog toner patch sensing network sends an analog signal 11 to microprocessor 12 by way of analog-to-digital converter 13. The reflectance of photoconductor drum 14 is measured (1) at a bare photoconductor area, or patch, and (2) at a developed area of the photoconductor.

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 87% of the total text.

Page 1 of 2

Self-Adjusting Analog Toner Patch Sensor

In a xerographic toner concentration sensor of the patch sensor type, a reference voltage defines the magnitude of the reflected light signal which should be received when the photocell views the bare photoconductor patch. Energization of the light source is controlled to make this reflected light signal equal in magnitude to this reference voltage. In this way, the light reflected from the photoconductor's toned patch is compared to an accurate reference reflectance, during the process of determining the need to add toner. The analog toner patch sensing network sends an analog signal 11 to microprocessor 12 by way of analog-to-digital converter 13. The reflectance of photoconductor drum 14 is measured (1) at a bare photoconductor area, or patch, and (2) at a developed area of the photoconductor. These two reflectances are indicated by the magnitude of the two signals generated by photocell 18, as the photocell first views one photoconductor area and then the other photoconductor area. The ratio of these two signals is calculated by the microprocessor, and a decision is made as to the need to add toner to the developer (not shown). The reflectance from the photoconductor's bare patch is monitored by the microprocessor on each measurement cycle, and a signal 15 is supplied to duty-cycle-to-current converter 16, thereby to increase or decrease energization of light-emitting diode (LED) 17, in order to maintain reflectance fr...