Image forming apparatus that has sheet sensor

Patent metadata

Field	Value
Publication number	US-2019137930-A1
Application number	US-201816181880-A
Country	US
Kind code	A1
Filing date	Nov 6, 2018
Priority date	Nov 7, 2017
Publication date	May 9, 2019
Grant date	—

Abstract

An image forming apparatus comprises a light-emission unit, a reflecting member, a light-receiving unit, a detection unit, a ventilation unit configured to send air to the reflecting member; and a control unit. The control unit adjusts at least one of an operation duration and an airflow rate of the ventilation unit, in accordance with a detection signal outputted by the light-receiving unit when a sheet is not at a position where light crosses a conveyance path.

First claim

What is claimed is:

1 . An image forming apparatus comprising:
a light-emission unit configured to emit light; a reflecting member that reflects the light emitted from the light-emission unit; a light-receiving unit configured to receive the light reflected from the reflecting member, the light crossing a conveyance path, on which a sheet is conveyed, one or more times from the light-emission unit until reaching the light-receiving unit; a detection unit configured to detect, based on a detection signal that the light-receiving unit outputs in accordance with an amount of light received, whether a sheet is at a position where light crosses the conveyance path; a ventilation unit configured to send air to the reflecting member; and a control unit configured to adjust at least one of an operation duration and an airflow rate of the ventilation unit, in accordance with the detection signal outputted by the light-receiving unit when a sheet is not at the position where light crosses the conveyance path.

2 . The image forming apparatus according to claim 1 ,
wherein the control unit is configured to, when a level of the detection signal does not exceed a dew condensation threshold value, increase the airflow rate of the ventilation unit or continue ventilation by the ventilation unit, and when a level of the detection signal exceeds a dew condensation threshold value, reduce the airflow rate of the ventilation unit or stop ventilation by the ventilation unit.

3 . The image forming apparatus according to claim 2 , further comprising:
a measurement unit configured to measure the operation duration of the ventilation unit, wherein, when the level of the detection signal does not exceed the dew condensation threshold value even if the operation duration measured by the measurement unit is greater than or equal to a predetermined amount of time, the control unit reduces the airflow rate of the ventilation unit or stops ventilation by the ventilation unit.

4 . The image forming apparatus according to claim 1 , wherein
the control unit causes the ventilation unit to operate while the image forming apparatus is forming an image on a sheet, and, when the image forming apparatus finishes forming the image on the sheet, adjusts at least one of the airflow rate and the operation duration of the ventilation unit in accordance with a detection signal outputted by the light-receiving unit when there is no sheet at the position where light crosses in the conveyance path.

5 . The image forming apparatus according to claim 1 , wherein
when power is supplied from a power supply and the image forming apparatus activates or when the image forming apparatus returns from a state where image formation is not performed to a state where image formation can be performed, the control unit causes the light-emission unit to output light, and drives or stop the ventilation unit, in accordance with the detection signal outputted by the light-receiving unit.

6 . The image forming apparatus according to claim 5 ,
wherein the control unit is configured to, when a level of the detection signal does not exceed a dew condensation threshold value, start ventilation by the ventilation unit or increase the airflow rate of the ventilation unit, and when a level of the detection signal exceeds a dew condensation threshold value, reduce the airflow rate of the ventilation unit or do not perform ventilation by the ventilation unit.

7 . The image forming apparatus according to claim 1 , wherein
when power is supplied from a power supply and the image forming apparatus activates or when the image forming apparatus returns from a state where image formation is not performed to a state where image formation can be performed, the control unit causes the light-emission unit to output light, causes the ventilation unit to start ventilation, and in accordance with the detection signal outputted by the light-receiving unit stops the ventilation unit, or adjusts the amount of light emitted by the light-emission unit or a gain of the light-receiving unit.

8 . The image forming apparatus according to claim 7 ,
wherein the control unit is configured to, continue ventilation by the ventilation unit when a level of the detection signal is not greater than or equal to a lower limit value of a predetermined range, and when a level of the detection signal is greater than or equal to the lower limit value of the predetermined range, reduce the airflow rate of the ventilation unit or stop ventilation by the ventilation unit.

9 . The image forming apparatus according to claim 8 , further comprising:
a measurement unit configured to measure the operation duration of the ventilation unit, wherein, in a case where the level of the detection signal is no greater than or equal to the lower limit value of the predetermined range even if the operation duration measured by the measurement unit is greater than or equal to a predetermined amount of time, the control unit increases the amount of light emitted by the light-emission unit or increases the gain of the light-receiving unit.

10 . The image forming apparatus according to claim 9 , wherein
the control unit increases the gain of the light-receiving unit if the level of the detection signal is not greater than or equal to the lower limit value of the predetermined range, even if the amount of light emitted by the light-emission unit is increased to a maximum value that can be set.

11 . The image forming apparatus according to claim 9 , wherein
the control unit increases the amount of light emitted by the light-emission unit in a case where the level of the detection signal is not greater than or equal to the lower limit value of the predetermined range, even if the gain of the light-receiving unit is increased to a maximum value that can be set.

12 . The image forming apparatus according to claim 9 , further comprising:
a storage unit configured to store, as an initial value, an amount of illumination light by the light-emission unit when the level of the detection signal is within the predetermined range, wherein the control unit sets the light-emission unit to the initial value stored in the storage unit when starting light emission by the light-emission unit.

13 . The image forming apparatus according to claim 9 , further comprising:
a storage unit configured to store, as an initial value, a gain of the light-receiving unit when the level of the detection signal is within the predetermined range, wherein the control unit sets the light-receiving unit to the initial value stored in the storage unit when starting reception of light by the light-receiving unit.

14 . The image forming apparatus according to claim 1 , further comprising:
a ventilation duct that guides air that is blown out from the ventilation unit or sucked in by the ventilation unit to the reflecting member so that the reflecting member is ventilated with the air.

15 . The image forming apparatus according to claim 1 , further comprising:
a first guide member and a second guide member that guide a sheet and are provided facing each other in the conveyance path, wherein the light-emission unit and the light-receiving unit are fixed to the first guide member, and the reflecting member is fixed to the second guide member.

16 . The image forming apparatus according to claim 1 , further comprising:
a light-shielding member provided between the light-emission unit and the light-receiving unit.

17 . The image forming apparatus according to claim 1 , furth

Assignees

• Canon Kk

Inventors

• Ishida Tsutomu
• Inoue Tomonari
• Abe Kenji
• Kuwata Takashi
• Nakajima Keita
• Katahira Ko
• Osada Takehito

Classifications

• G03G15/70

  Detecting malfunctions relating to paper handling, e.g. jams · CPC title

• G03G2215/00611

  Detector details, e.g. optical detector · CPC title

• G03G15/6576

  Decurling of sheet material · CPC title

• G03G2215/00616

  Optical detector · CPC title

• G03G2215/00548

  Jam, error detection, e.g. double feeding · CPC title