Search

US-12617638-B2 - Sheet feeding device and image forming apparatus

US12617638B2US 12617638 B2US12617638 B2US 12617638B2US-12617638-B2

Abstract

A sheet feeding device includes a lift plate, a feeding portion, a lifting member lifting the lift plate, a motor coupled to a pivot shaft serving as the pivot fulcrum of the lifting member, a control portion, and an encoder outputting a pulse signal according to the rotation of the pivot shaft. The encoder includes a rotary member and an optical sensor. The control portion recognizes the remaining quantity of sheets on the lift plate based on the count value of the pulse signal. When the motor stops being driven, the control portion thereafter does not count the pulse signal until a predetermined period elapses.

Inventors

  • Toshiaki Inoue

Assignees

  • KYOCERA DOCUMENT SOLUTIONS INC.

Dates

Publication Date
20260505
Application Date
20250103
Priority Date
20240112

Claims (5)

  1. 1 . A sheet feeding device comprising: a lift plate on which a sheet is set; a feeding portion that contacts the sheet on the lift plate from above to pull and feed the sheet out from the lift plate; a lifting member that is disposed under the lift plate, the lifting member lifting the lift plate by making one end of the lifting member in a feeding direction pivot upward about another end of the lifting member in the feeding direction serving as a pivot fulcrum, the lifting member thereby bringing the sheet on the lift plate into contact with the feeding portion; a motor that is coupled to a pivot shaft serving as a pivot fulcrum of the lifting member, the motor rotating the pivot shaft and thereby making the one end of the lifting member pivot upward; a control portion that controls the motor, the control portion stopping driving the motor when the sheet on the lift plate contacts the feeding portion; and an encoder that outputs a pulse signal according to rotation of the pivot shaft, wherein the encoder includes: a rotary member that has a plurality of sensing targets arranged at intervals from each other in a circumferential direction of the pivot shaft, the rotary member rotating together with the pivot shaft; and an optical sensor that has a light emitter and a light receiver disposed so as to face each other across a movement path of the plurality of the sensing targets, the optical sensor changing a level of the pulse signal between when the light from the light emitter reaches the light receiver and when the light from the light emitter does not reach the light receiver, the control portion recognizes a remaining quantity of the sheets on the lift plate based on a count value of the pulse signal, when the motor stops being driven, the control portion thereafter does not count the pulse signal until a predetermined period elapses, when the motor stops being driven, the rotary member swings in the circumferential direction under vibration generated in the sheet feeding device, when the level of the pulse signal changes from a first level to a second level, the control portion increments the count value, when the motor stops being driven at a timing of the pulse signal changing from the first level to the second level, even if the pulse signal changes from the first level to the second level in the predetermined period, the control portion increments the count value only once, and, when the light from the light emitter does not reach the light receiver, the pulse signal at the first level is output from the encoder, and, when the light from the light emitter reaches the light receiver, the pulse signal at the second level is output from the encoder.
  2. 2 . The sheet feeding device according to claim 1 , wherein when the motor stops being driven at the timing of the change of the pulse signal from the second level to the first level, even if the pulse signal changes from the first level to the second level in the predetermined period, the control portion does not increment the count value.
  3. 3 . The sheet feeding device according to claim 1 , wherein, when the motor starts to be driven, the rotary member swings in the circumferential direction under vibration generated in the sheet feeding device, and when the motor starts to be driven, the control portion thereafter does not count the pulse signal until a period having a length equal to a length of the predetermined period elapses.
  4. 4 . The sheet feeding device according to claim 1 , wherein the rotary member has reference regions, across which the interval between the sensing targets adjacent to each other in the circumferential direction is set to a predetermined interval, at regular intervals in the circumferential direction, on judging that the remaining quantity of the sheet on the lift plate is full, from the state where the optical sensor is sensing the reference region, the control portion starts to lift the lift plate, and after starting to lift the lift plate, when the optical sensor senses the reference region a next time, the control portion judges that the remaining quantity of the sheet has become equal to or less than a predetermined quantity.
  5. 5 . An image forming apparatus comprising: the sheet feeding device according to claim 1 , wherein the image forming apparatus prints an image on the sheet fed from the sheet feeding device.

Description

INCORPORATION BY REFERENCE This application is based on and claims the benefit of priority from Japanese Patent Application No. 2024-003109 filed on Jan. 12, 2024, the contents of which are hereby incorporated by reference. BACKGROUND The present disclosure relates to a sheet feeding device and an image forming apparatus. Conventional sheet feeding devices feed a sheet stored in a storage portion by pulling the sheet out from the storage portion. In the conventional sheet feeding device, sheets are set on a lift plate. When one sensor detects that the sheets on the lift plate are at an upper limit position and another sensor detects that the lift plate is at a lower limit position, the remaining quantity of sheets is considered to be 100%. Based on the ascending time of the lift plate from that time point, the remaining quantity of sheets is found. SUMMARY According to a first aspect of the present disclosure, a sheet feeding device includes a lift plate, a feeding portion, a lifting member, a motor, a control portion, and an encoder. The lift plate has sheets set on it. The feeding portion contacts the sheet on the lift plate from above to pull and feed the sheet out from the lift plate. The lifting member is disposed under the lift plate, lifts the lift plate by making one end of the lifting member in the feeding direction pivot upward about the other end of the lifting member in the feeding direction serving as a pivot fulcrum, and thereby brings the sheet on the lift plate into contact with the feeding portion. The motor is coupled to a pivot shaft serving as the pivot fulcrum of the lifting member, rotates the pivot shaft and thereby makes the one end of the lifting member pivot upward. The control portion controls the motor and stops driving the motor when the sheet on the lift plate contacts the feeding portion. The encoder outputs a pulse signal according to rotation of the pivot shaft. The encoder includes a rotary member and an optical sensor. The rotary member has a plurality of sensing targets arranged at intervals from each other in the circumferential direction of the pivot shaft, and rotates together with the pivot shaft. The optical sensor has a light emitter and a light receiver disposed so as to face each other across the movement path of the plurality of sensing targets and changes the level of the pulse signal between when the light from the light emitter reaches the light receiver and when it does not. The control portion recognizes the remaining quantity of sheets on the lift plate based on the count value of the pulse signal. When the motor stops being driven, the control portion does not count the pulse signal after the motor stops being driven until a predetermined period elapses. According to a second aspect of the present disclosure, an image forming apparatus includes the sheet feeding device described above and prints an image on a sheet fed from the sheet feeding device. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an image forming apparatus according to an embodiment. FIG. 2 is a schematic diagram showing an image forming portion according to the embodiment. FIG. 3 is a block diagram of the image forming apparatus according to the embodiment. FIG. 4 is a schematic diagram showing a sheet feeding device according to the embodiment. FIG. 5 is a schematic diagram showing an encoder according to the embodiment. FIG. 6 is a plane view of a rotary member of the encoder in FIG. 5. FIG. 7 is a diagram showing the positional relationship between an optical sensor and sensing segments in the encoder in FIG. 5. FIG. 8 is a diagram showing a pulse signal output from the encoder according to the embodiment. FIG. 9 is a diagram showing the relationship between the driving stop time point of a lift motor (the time point of a level change from H to L) and a predetermined period according to the embodiment. FIG. 10 is a diagram showing the relationship between the driving start time point of the lift motor (the time point of a level change from L to H) and a predetermined period according to the embodiment. DETAILED DESCRIPTION Now, an embodiment of the present disclosure will be described taking as an example a tandem color laser printer. The present disclosure finds applications in not only printers but also multifunction peripherals having copying and other functions. Moreover, the present disclosure finds applications in not only color machines but also monochrome machines. Construction of the Image Forming Apparatus: FIG. 1 shows a construction of an image forming apparatus 1000 according to the embodiment. The image forming apparatus 1000 is installed on a flat floor surface FL. The image forming apparatus 1000 has, as its top-bottom directions, directions perpendicular to the floor surface FL. The image forming apparatus 1000 includes a main conveyance passage MP (indicated by a bold broken arrow). The main conveyance passage MP reaches an ejection tray ET via