# US 6,724,506 B1 · Method and apparatus for measuring and indicating paper level in a sheet-feeding device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,724,506 B1 - Document ID: US6724506B1 - Status: Granted - Kind: B1 - Application number: 09/722,426 - Filed: 2000-11-28 - Granted: 2004-04-20 - Earliest claimed: 2000-11-28 - Assignees: Aetas Technology Incorporated - Inventors: Bobo Wang - Web page: https://patentgrep.com/patent/US6724506B1 ## CPC - H04N 1/00588: {to the scanning position (H04N1/00572, H04N1/00594 take precedence)} - H04N 1/0057: {Conveying sheets before or after scanning (arrangements for conveying sheets as part of the scanning operation H04N1/04 and subgroups)} - H04N 1/00602: {Feed rollers} - H04N 1/0062: {Removing sheets from a stack or inputting media} - H04N 1/00644: {Counting or calculating, e.g. a number of remaining sheets} - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An imaging system includes an imaging subsystem for forming an image on a sheet, a tray for holding a supply of sheets, a ramp for directing a sheet from the tray into a paper path, a sensor in the vicinity of the paper path, a drive assembly and a processor connected to the drive assembly and the sensor. The drive assembly includes a movable roller configured to move the sheet into the paper path by moving a top sheet of a supply of sheets in the tray to the ramp. The sensor is configured to detect a sheet traveling in the paper path from the tray and to provide an output signal in response to the detection. The processor is configured to control movement of the roller, to receive and store an initial sheet level value, to receive the output signal from the sensor and to calculate a time, t, from activating the drive assembly to receiving the sensor output signal and to accordingly adjust the initial sheet level value. In a method for measuring sheet levels in an imaging system paper tray, a start time that a roller engages a paper sheet to feed the sheet from the paper tray to a paper path of the imaging system is recorded and a time the sheet passes a location along the paper path is sensed. A time difference between the start time and the time sensed is processed to provide a signal that represents a supply of sheets in the paper tray. ## Claims ### Claim 1 An imaging system, comprising an imaging subsystem for forming an image on a sheet, a tray for holding a supply of sheets; a ramp for directing a sheet from the tray into a paper path; a drive assembly including a movable roller configured to move the sheet into the paper path by moving a top sheet of a supply of sheets in the tray to the ramp; a sensor in the vicinity off the paper path and configured to detect a sheet traveling in the paper path from the tray and to provide an output signal in response thereto; and a processor connected to the drive assembly and the sensor; the processor configured to control movement of the roller, to receive and store an initial sheet level value, to receive the output signal from the sensor and to calculate a time, t, from activating the drive assembly to receiving the sensor output signal, to calculate a distance d from a known angular velocity V of the roller and time t and to accordingly adjust the initial sheet level value. ### Claim 2 (depends on 1) The imaging system of claim 1, wherein the processor is configured to store a total distance D between a location of the tray and the sensor and to calculated a distance s as the difference between distances D and d and to accordingly adjust the initial sheet level value. ### Claim 3 (depends on 1) The imaging system of claim 1, wherein the processor is configured to compare distances with a known set of distances in a look-tip table and to accordingly adjust the initial sheet level value. ### Claim 4 (depends on 1) The imaging system of claim 1, wherein t is calculated as a span of time between activating the drive assembly and detection of a leading edge of the paper by the sensor. ### Claim 5 (depends on 1) The imaging system of claim 1, additionally comprising a display connected to the processor to display an indication of the sheet level value stored in the processor. ### Claim 6 (depends on 1) The imaging system of claim 1, wherein the drive assembly includes a pick roller for moving a top sheet of the supply of sheets in the tray to the ramp; the drive assembly being configured to maintain a constant roller stroke distance between the roller and the ramp when the roller is moving the top sheet to the ramp. ### Claim 7 (depends on 6) The imaging system of claim 6 wherein the drive assembly is configured to maintain the roller stroke distance constant independent of a level of the supply of sheets in the tray. ### Claim 8 (depends on 1) The imaging system of claim 1, additionally comprising a step motor to drive the imaging system. ### Claim 9 (depends on 8) The imaging system of claim 8, wherein the processor is further configured to store a gear ratio value of the step motor to the roller, to count a number of steps or the motor between pick up of a paper sheet by tile roller to receipt of the output signal from the sensor and to convert the count into a distance value. ### Claim 10 (depends on 1) The imaging system of claim 1 wherein the imaging subsystem is configured to form images electrophotographically. ### Claim 11 An imaging system comprising: an imaging subsystem for forming an image on a sheet; a tray for holding a supply of sheets; a ramp for directing a sheet from the tray to the imaging subsystem; a drive assembly including a roller for moving a top sheet of the supply of sheets in the tray to the ramp with a reciprocating roller stroke; the drive assembly being configured to maintain a constant roller stroke distance between the roller and the ramp independent of a level of the supply of sheets in the tray; a sensor in the vicinity of the paper path and configured to detect a sheet traveling in the paper path from the tray and to provide an output signal in response thereto; and a processor connected to the sensor; the processor configured to receive the sensor output signal and to accordingly adjust a value representing a sheet level in the tray. ### Claim 12 (depends on 11) The imaging system of claim 11 wherein the imaging subsystem is configured to form images electrophotographically. ### Claim 13 A method for measuring sheet levels in an imaging system paper tray, comprising: recording a start time that a roller engages a paper to feed the sheet from the paper tray to a paper path of the imaging system; sensing a time the paper passes a location along the paper path; and processing a time difference, t, between the start time and the time sensed to provide a signal that represents a supply of sheets in the paper tray wherein a distance d is calculated from a known angular velocity V of a roller that engages the paper to establish the start time and time t and the signal that represents the supply of sheets in the paper tray is accordingly adjusted. ### Claim 14 (depends on 13) The method of claim 13, comprising sensing a time at railing edge of the paper passes the location. ### Claim 15 (depends on 13) The method of claim 13, wherein the imaging system is an electrophotographic imaging system. ### Claim 16 (depends on 13) The method of claim 13 comprising storing a value that represents a total distance D between a location of the tray and the sensor and to calculated a distance s as the difference between distances D and d and to accordingly adjust the signal that represents the supply of sheets in the paper tray; ### Claim 17 (depends on 16) The method of claim 16, comprising comparing distances with a known set of distances in a look-up table and accordingly adjusting the signal that represents the supply of sheets in the paper tray. ### Claim 18 (depends on 13) The method of claim 13, comprising displaying the signal representing the supply of sheets. ### Claim 19 An imaging system, comprising an imaging subsystem for forming an image on a sheet, a tray for holding a supply of sheets; a ramp for directing a sheet from the tray into a paper path; a drive assembly including a movable pick roller for moving a top sheet of the supply of sheets in the tray to the ramp; the drive assembly being configured to maintain a constant roller stroke distance between the roller and the ramp independent of a level of the supply of sheets in the tray when the roller is moving the top sheet to the ramp; a sensor in the vicinity of the paper path and configured to detect a sheet traveling in the paper path from the tray and to provide an output signal in response thereto; and a processor connected to the drive assembly raid the sensor; the processor configured to control movement of the roller, to receive and store an initial sheet level value, to receive the output signal from the sensor and to calculate a time, t, form activating the drive assembly to receiving the sensor output signal and to accordingly adjust the initial sheet level value.