Image forming apparatus

Patent metadata

Field	Value
Publication number	US-9563165-B2
Application number	US-201514664054-A
Country	US
Kind code	B2
Filing date	Mar 20, 2015
Priority date	Mar 20, 2014
Publication date	Feb 7, 2017
Grant date	Feb 7, 2017

Abstract

An image forming apparatus feeds a recording sheet from a sheet feed roller, clamps the recording sheet between an image carrier and a transfer roller, transfers a toner image to the recording sheet from the image carrier while conveying the recording sheet, and fixes the transferred toner image on the recording sheet. Recording sheets are stacked on an elevating plate. An elevating plate swinging mechanism vertically swings the elevating plate. A rotation drive mechanism rotates the sheet feed roller in synchronism with the elevating plate swinging mechanism. A recording sheet detector detects a leading edge of each recording sheet fed from the sheet feed roller. A conveyance controller measures sheet feed time from starting a sheet feed operation to detecting the leading edge of the recording sheet. Based on the measured sheet feed time, the conveyance controller sets a sheet feed start timing of a next recording sheet.

First claim

What is claimed:

1. An image forming apparatus configured to feed a recording sheet from a sheet feed roller, clamp the recording sheet between an image carrier and a transfer roller, transfer a toner image to the recording sheet from the image carrier while conveying the recording sheet, and fix the transferred toner image on the recording sheet at a fixing unit, the image forming apparatus comprising:
an elevating plate on which recording sheets are stacked;
an elevating plate swinging mechanism configured to swing the elevating plate to move vertically;
a rotation drive mechanism configured to rotate the sheet feed roller in synchronism with the elevating plate swinging mechanism;
a recording sheet detector configured to detect a leading edge of each recording sheet fed from the sheet feed roller; and
a conveyance controller configured to drive the elevating plate swinging mechanism to swing the elevating plate and configured to rotate the sheet feed roller to feed a recording sheet, a time interval from start of a preceding recording sheet feed operation by the sheet feed roller to start of a next recording sheet feed operation being controlled to be a fixed time interval between a plurality of consecutive recording sheets,
the conveyance controller being configured to, when executing a sheet feed operation of the recording sheet, measure sheet feed time from starting the sheet feed operation to detecting the leading edge of the recording sheet by the recording sheet detector, and configured to set a sheet feed start timing for starting a sheet feed operation of a next recording sheet based on the measured sheet feed time.

2. The image forming apparatus according to claim 1 , wherein the conveyance controller is configured to measure, as the sheet feed time, time from starting to drive the elevating plate swinging mechanism to detecting the leading edge of the recording sheet by the recording sheet detector.

3. The image forming apparatus according to claim 1 , wherein the conveyance controller is configured to, as the sheet feed time increases, set time until the sheet feed start timing at a smaller value.

4. The image forming apparatus according to claim 1 , further comprising a data table indicating a relationship between sheet feed interval time until a next sheet feed start timing and the sheet feed time,
wherein the conveyance controller is configured to measure the sheet feed time, refer to the data table, calculate the sheet feed interval time, and set the sheet feed start timing.

5. The image forming apparatus according to claim 1 , wherein the conveyance controller is configured to, based on the measured sheet feed time, predict a number of the recording sheets stacked on the elevating plate.

6. The image forming apparatus according to claim 5 , further comprising a data table indicating a relationship between the number of the recording sheets stacked on the elevating plate and the sheet feed time,
wherein the conveyance controller is configured to measure the sheet feed time, refer to the data table, and predict the number of the stacked recording sheets.

7. The image forming apparatus according to claim 5 , further comprising a display configured to display the number of the recording sheets stacked on the elevating plate,
wherein the number of the stacked recording sheets, which has been predicted by the conveyance controller, is displayed in the display.

8. The image forming apparatus according to claim 1 , further comprising a recording sheet separator configured to move between a position in contact with the sheet feed roller and a position separate from the sheet feed roller in synchronism with the elevating plate moving vertically.

9. The image forming apparatus according to claim 2 , wherein the conveyance controller is configured to, as the sheet feed time increases, set time until the sheet feed start timing at a smaller value.

10. The image forming apparatus according to claim 2 , further comprising a data table indicating a relationship between sheet feed interval time until a next sheet feed start timing and the sheet feed time,
wherein the conveyance controller is configured to measure the sheet feed time, refer to the data table, calculate the sheet feed interval time, and set the sheet feed start timing.

11. The image forming apparatus according to claim 3 , further comprising a data table indicating a relationship between sheet feed interval time until a next sheet feed start timing and the sheet feed time,
wherein the conveyance controller is configured to measure the sheet feed time, refer to the data table, calculate the sheet feed interval time, and set the sheet feed start timing.

12. The image forming apparatus according to claim 9 , further comprising storing a data table indicating a relationship between sheet feed interval time until a next sheet feed start timing and the sheet feed time,
wherein the conveyance controller is configured to measure the sheet feed time, refer to the data table, calculate the sheet feed interval time, and set the sheet feed start timing.

13. The image forming apparatus according to claim 2 , wherein the conveyance controller is configured to, based on the measured sheet feed time, predict a number of the recording sheets stacked on the elevating plate.

14. The image forming apparatus according to claim 3 , wherein the conveyance controller is configured to, based on the measured sheet feed time, predict a number of the recording sheets stacked on the elevating plate.

15. The image forming apparatus according to claim 4 , wherein the conveyance controller is configured to, based on the measured sheet feed time, predict a number of the recording sheets stacked on the elevating plate.

16. The image forming apparatus according to claim 9 , wherein the conveyance controller is configured to, based on the measured sheet feed time, predict a number of the recording sheets stacked on the elevating plate.

17. The image forming apparatus according to claim 10 , wherein the conveyance controller is configured to, based on the measured sheet feed time, predict a number of the recording sheets stacked on the elevating plate.

18. The image forming apparatus according to claim 11 , wherein the conveyance controller is configured to, based on the measured sheet feed time, predict a number of the recording sheets stacked on the elevating plate.

19. The image forming apparatus according to claim 12 , wherein the conveyance controller is configured to, based on the measured sheet feed time, predict a number of the recording sheets stacked on the elevating plate.

20. The image forming apparatus according to claim 6 , further comprising a data table indicating a relationship between the number of the recording sheets stacked on the elevating plate and the sheet feed time,
wherein the conveyance controller is configured to measure the sheet feed time, refer to the data table, and predict the number of the stacked recording sheets.

21. The image forming apparatus of claim 1 , wherein the elevating plate swinging mechanism is structured to move the elevating plate each time the recording sheets are fed one by one.

Assignees

• Konica Minolta Inc

Inventors

• Nakamura Yasuo

Classifications

• B65H2220/02

  indicating an entity which is controlled, adjusted or changed by a control process, i.e. output · CPC title

• B65H2403/47

  Ratchet · CPC title

• B65H2513/50

  Timing · CPC title

• B65H2220/01

  indicating an entity as a function of which control, adjustment or change is performed, i.e. input · CPC title

• B65H7/08

  responsive to incorrect front register · CPC title