Recording sheet feeding device

A sheet feeding device having a tray on which a plurality of sheets are stacked in a stack, feeding means for feeding said sheets stacked in said stack by contact therewith, separation means provided downstream of said feeding means in a downstream feeding direction, for separating said stacked sheets, one by one, from said stack, and at least one pair of conveyance rollers provided downstream of said separation means, in said downstream feeding direction, for conveying each of said separated sheets, said sheet feeding device further comprising:

• (a) setting means for setting a plurality of characteristics of said sheets before a sheet feeding is started and for generating a setting means output signal;
• (b) size detection means for detecting a size of said sheets in said stack, and for generating a size detection output signal indicative of the detected size of said sheets in said stack;
• (c) pressing means for applying an adjustable pressure to said sheets in said stack so that a contact pressure between said feeding means and said stack is adjustable based on said size detection output signal from said size detection means;
• (d) sheet edge detecting means provided downstream of said separation means, in said downstream feeding direction, for detecting an edge portion of each of said separated sheets;
• (e) first and second driving means for driving said feeding means, said pressing means and said at least one pair of conveyance rollers;
• and
• (f) control means for controlling said first and second driving means;
• and wherein:
• (g) said control means controls at least one of said first and second driving means in accordance with said setting means output signal.

A sheet feeding device having a tray on which a plurality of sheets are stacked in a stack, feeding means for feeding said sheets stacked in said stack by contact therewith, separation means provided downstream of said feeding means in a downstream feeding direction, for separating said stacked sheets, one by one, from said stack, and at least one pair of conveyance rollers provided downstream of said separation means, in said downstream feeding direction, for conveying each of said separated sheets, said sheet feeding device further comprising:

• (a) size detection means for detecting a size of said sheets in said stack, and for generating a size detection output signal indicative of the detected size of said sheets in said stack;
• (b) pressing means for adjustably pressing said sheets in said stack so that a contact pressure between said feeding means and said sheets in said stack is adjustable based on said size detection output signal from said size detection means;
• (c) sheet edge detecting means provided downstream of said separation means, in said downstream feeding direction, for detecting an edge portion of each of said separated sheets;
• (d) first and second driving means for driving said feeding means, said pressing means and said at least one pair of conveyance rollers;
• (e) control means for controlling said first and second driving means;
• (f) measuring means for measuring a time period between a start of a sheet feeding operation and a time when a leading edge of a sheet is detected by said sheet edge detecting means;
• and
• (g) comparing means for comparing the time period measured by said measuring means with a preset reference time period;
• and wherein:
• when a difference of the time periods compared by said comparing means exceeds a predetermined value, a pressing force of said pressing means that is applied to a subsequently fed sheet is changed.

A sheet feeding device comprising:

• (a) a tray on which a plurality of sheets are stacked in a stack;
• (b) feeding means for feeding the sheets in said stack by a contact therewith;
• (c) a movable member provided at part of said tray, for holding and pressing the sheets toward said feeding means by a moving operation of said movable member;
• (d) an elastic member coupled to a drive member;
• (e) said drive member moving said movable member through said elastic member;
• (f) driving means for driving said drive member toward said elastic member;
• (g) a first detection member for detecting at least one of a deformation amount of said elastic member and a relative position between said movable member and said drive member when said drive member is moved through said elastic member;
• (h) separation means provided downstream of said feeding means, in a downstream feeding direction, for separating said sheets, one by one, from the stack;
• (i) a second detection member provided downstream of said separation means, in said downstream feeding direction, for detecting an edge portion of a separated sheet;
• and
• (j) control means for controlling said feeding means and said driving means by controlling at least one of a feeding operation of said feeding means and a driving operation of said driving means to control a movement of sheets through said sheet feeding device.

A sheet feeding device comprising:

• (a) a tray on which a plurality of sheets are stacked in a stack;
• (b) feeding means for feeding the sheets in said stack by a contact therewith;
• (c) a movable member provided at part of said tray, for holding the sheets and for pressing said feeding means toward the sheets by a moving operation of said movable member;
• (d) an elastic member coupled to a drive member;
• (e) said drive member moving said movable member through said elastic member;
• (f) driving means for driving said drive member toward said elastic member;
• (g) a first detection member for detecting at least one of a deformation amount of said elastic member and a relative position between said movable member and said drive member when said drive member is driven through said elastic member by said driving means;
• (h) separation means provided downstream of said feeding means, in a downstream feeding direction, for separating said sheets one by one from the stack;
• (i) at least a pair of conveyance rollers provided downstream of said separation means, in said downstream feeding direction, for conveying the sheets separated by said separation means;
• (j) a second detection member provided downstream of said separation means, in said downstream feeding direction, for detecting an edge portion of a separated sheet;
• and
• (k) control means for controlling said feeding means, said driving means and said conveyance rollers, for controlling a movement of sheets through said sheet feeding device.

A sheet feeding device having a tray on which a plurality of sheets are stacked in a stack, feeding means for feeding said sheets stacked in said stack by contact therewith, separation means provided downstream of said feeding means in a downstream feeding direction, for separating said stacked sheets, one by one, from said stack, and at least one pair of conveyance rollers provided downstream of said separation means, in said downstream feeding direction, for conveying each of said separated sheets, said sheet feeding device further comprising:

• (a) a rotation member in said feeding means for feeding sheets from said stack;
• (b) a pressing member for pressing the sheets toward said rotation member;
• (c) a drive member arranged for moving said pressing member;
• (d) an elastic member coupled to a drive member;
• (e) drive means for driving said drive member toward said elastic member;
• (f) size detection means for detecting a size of said sheets in the stack;
• (g) at least one first detection member for detecting a relative position between said pressing member and said drive member;
• (h) control means for controlling a movement of said drive member;
• (i) a second detection member for detecting a home position of said pressing member, said sheets being stacked between said rotation member and said pressing member;
• (j) a third detection member for detecting an edge portion of a separated sheet;
• and
• (k) measuring means for measuring a distance travelled during a period of time that begins when one of a drive operation of said drive means and a detection operation by said second detection member occurs and ends at another time when a detection by said at least one first detection member occurs, and wherein a thickness of sheets stacked in said stack is detected based on a measured value of the distance travelled during said period of time.

A sheet feeding device having a tray on which a plurality of sheets are stacked in a stack, feeding means for feeding said sheets stacked in said stack by contact therewith, separation means provided downstream of said feeding means in a downstream feeding direction, for separating said stacked sheets, one by one, from said stack, and at least one pair of conveyance rollers provided downstream of said separation means, in said downstream feeding direction, for conveying each of said separated sheets, said sheet feeding device further comprising:

• (a) a rotation member for feeding a sheet;
• (b) an elastic member coupled to a drive member;
• (c) a pressing member for pivotally holding said rotation member;
• (d) said drive member pressing said pressing member through said elastic member;
• (e) driving means for driving said drive member toward said pressing member;
• (f) size detection means for detecting a size of said sheets in said stack;
• (g) at least one first detection member for detecting a relative position between said pressing member and said drive member;
• (h) control means for controlling a movement of said drive member;
• (i) a second detection member for detecting a home position of the pressing member;
• (j) a third detection member for detecting a trailing edge portion of a separated sheet;
• and
• (k) measuring means for measuring a distance travelled during a time period beginning when one of a drive operation of said driving means and a detection operative of said second detection member occurs and ending when a detection by said at least one first detection member occurs, and wherein a thickness of the sheets in said stack is detected based on a measured value of the distance travelled.

A sheet feeding device having a tray on which a plurality of sheets are stacked, feeding means for feeding said sheets stacked in said stack by contact therewith, separation means provided downstream of said feeding means in a downstream feeding direction, for separating said stacked sheets, one by one, from said stack, and at least one pair of conveyance rollers provided downstream of said separation means, in said downstream feeding direction, for conveying each of said separated sheets, said sheet feeding device further comprising:

• (a) pressing means for pressing said sheets in said stack so that a contact pressure is generated between said feeding means and said sheets in said stack;
• (b) an elastic member coupled to said pressing means;
• (c) a motor for moving said pressing means through said elastic member, said motor thereby changing said contact pressure;
• (d) a press detection sensor for detecting a contact between said feeding means and said sheets in said stack;
• and
• (e) control means for controlling said contact pressure in accordance with a number of turns of said motor after said press detection sensor has detected said contact.