Claims
- 1. A toner level sensor for detecting magnetic toner level in a developing unit, comprising:
- at least first and second magnetic circuits each having magnetic gaps, the coupling coefficient of one of said first and second magnetic circuits being set at a predetermined value equivalent to the coupling coefficient exhibited when the toner level lies within a predetermined range, the coupling coefficient of the other of said first and second magnetic circuits varying in proportion to the toner level;
- coil members wound about each of said first and second magnetic circuits for providing a differential output from said first and second magnetic circuits;
- means coupled to said first and second magnetic circuits for providing a reference A.C. signal; and
- phase detector means for comparing the phases of the differential output and the reference A.C. signal, and for providing an output indicative of the phase comparison as an indication of toner level.
- 2. A toner level sensor according to claim 1, further comprising comparator means for comparing the output of said phase detector means with a reference value.
- 3. A toner level sensor according to claim 1, wherein said first and second magnetic circuits include two symmetrically disposed magnetic cores of like shape and size.
- 4. A toner level sensor according to claim 1, wherein said first and second magnetic circuits have a common magnetic path portion.
Priority Claims (2)
Number |
Date |
Country |
Kind |
57-120781 |
Jul 1982 |
JPX |
|
JP83/00222 |
Jul 1983 |
WOX |
|
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. application Ser. No. 589,116, filed on Mar. 2, 1984, now abandoned.
US Referenced Citations (13)
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
589116 |
Mar 1984 |
|