Developing material amount detecting apparatus

Claim 2

A developing material amount detecting apparatus for detecting an amount of developing material contained in a tank comprising: a detection member provided inside said tank movably between a first position and a second position; means for urging said detection member towards said first position; means for periodically sending said detection member from said first position to said second position; and means for detecting, while said sending means is actuating, the amount of said developing material inside said tank in accordance with a length of time in which said detection member is being held in said first position.

Claim 3

A developing material amount detecting apparatus as claimed in claim 1, wherein said detecting means comprises a switching means which changes its state between first and second conditions, said first condition being established when said detection member is held substantially in said first position and said second condition being established when said detection member is held substantially in a position other than said first position, and a timer means for counting at least a time length when said switching means is in either one of said first and second conditions.

Claim 4

A developing material amount detecting apparatus as claimed in claim 2, wherein said detecting means further comprises a reference time length producing means for producing a reference time length and a comparator for comparing said time length counted by said counting means with said reference time length.

Claim 5

A developing material amount detecting apparatus as claimed in claim 3, wherein said reference time length is greater than zero and smaller than one cycle length of said sending means moving periodically.

Claim 6

A developing material amount detecting apparatus for detecting an amount of developing material contained in a tank comprising: a detection member provided inside said tank movably between a first position and a second position; means for urging said detection member towards said first position; means for periodically sending said detection member from said first position to said second position; and means for detecting a time length when said detection member is held substantially in said first position or in a position other than said first position, said time length representing an amount of developing material contained in said tank.

Claim 7

A developing material amount detecting apparatus for detecting an amount of developing material contained in a tank comprising: a detection member provided inside said tank movably between a first position and a second position; means for urging said detection member towards said first position; means for periodically sending said detection member from said first position to said second position; and means for detecting a time length when said detection member is held substantially in said first position or in a position other than said first position, said time length representing an amount of developing material contained in said tank.

Claim 8

A developing material amount detecting apparatus as claimed in claim 5, wherein said detecting means comprises: a switching means which is turned to a first condition when said detecting member is held substantially in said first position and is turned to a second condition when said detection member is held substantially in a position other than said first position; a timer means for counting a predetermined time length; means for starting said timer means when said switching means is turned to said second condition; and means for producing a signal when said switching means is maintained to said second condition for a time length longer than said predetermined time length.

Claim 9

A developing material amount detecting apparatus as claimed in claim 5, wherein said detecting means comprises: a switching means which is turned to a first condition when said detection member is held substantially in said first position and is turned to a second condition when said detection member is held substantially in a position other than said first position; a timer means for counting a predetermined time length; means for starting said timer means when said switching means is turned to said first condition; and means for producing a signal when said switching means is maintained at said first condition for a time length longer than said predetermined time length.

Claim 10

A developing material amount detecting apparatus as claimed in claim 5, wherein said detecting means comprises: a switching means which is turned to a first condition when said detection member is held substantially in said first position and is turned to a second condition when said detection member is held substantially in a position other than said first position; a first timer means for counting a first predetermined time length; means for starting said timer means in response to the turning of said switching means to said second condition; means for producing a signal indicating that the amount of developing material in said tank has increased above a predetermined amount when said switching means is maintained at said second condition for a time length longer than said first predetermined time length; a second timer means for counting a second predetermined time length; means for starting said timer means in response to the turning of said switching means to said first condition; and means for producing a signal indicating that the amount of developing material in said tank has decreased below a predetermined amount when said switching means is maintained at said first condition for a time length longer than said second predetermined time length.

Claim 11

A developing material amount detecting apparatus as claimed in claim 8, wherein said first and second timer means are defined by a single counter.