JPH05201584A - Image forming device - Google Patents

Abstract

PURPOSE:To clean an optical sensor automatically according to its use condition by operating an air brush in connection with the operation of a tray moving plate which is lowered when a sheet is fed. CONSTITUTION:When absence of a specified amount of sheets loaded on a tray moving plate 1A is detected by an optical sensor 6A, power transmission to a lift motor 2A is started and the tray moving plate 1A is started to lower to feed a sheet. In this case, an air tank for an air brush 17A is compressed by a contact plate 18A and a tray moving plate 1A while the sheet is moved from near its lower limit to the lower limit, and air is sprayed from an air nozzle of it to the optical sensor 6A. As a result, paper dust, dirt, etc., adhered or accumulated on the surface of the optical sensor 6A when sheet feeding is made are blown off to clean it securely and prevent mis-detection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming system in which a plurality of sheets are stacked on a tray moving plate which is moved up and down to feed the sheets, and the sheets are detected by an optical sensor. It relates to the device.

[0002]

2. Description of the Related Art Conventionally, for example, a large-sized type or high-speed type copying machine as an image forming apparatus has adopted a deck paper feeding system capable of accommodating a large amount of paper, and can cope with a large number of copying. It was configured as shown in FIG. That is, 1A, 1B, and 1C are tray moving plates 2A, 2B, and 2C, which are arranged in the upper, middle, and lower stages of the deck and on which a plurality of sheets of different sizes are stacked, respectively. 1C, lift motors 3A, 3B and 3C respectively lift and lower tray moving plates 1A and 1A.
Guide grooves 4A, 4 for guiding the lifting of B and 1C respectively
B and 4C are deck upper limit switches 5A and 5A for detecting the upper limit position for feeding the tray moving plates 1A, 1B and 1C.
B and 5C are deck lower limit switches for detecting the lower limit position of the tray moving plates 1A, 1B and 1C for paper supply, 6
A, 6B, and 6C are provided on the back sides of the tray moving plates 1A, 1B, and 1C, respectively, and cutout portions 1AA, 1BA, and 1CA formed in the tray moving plates 1A, 1B, and 1C to the tray moving plates 1A, An optical sensor for detecting the presence or absence of sheets stacked on 1B and 1C.
B and 6C are, for example, the light emitting parts 7A, 7B and 7C and the light receiving part 8
A photo sensor composed of A, 8B, and 8C is shown in FIG.
As shown in, only when the paper P is on the tray moving plates 1A, 1B, 1C, the light from the light emitting portions 7A, 7B, 7C is reflected by the paper P and is incident on the light receiving portions 8A, 8B, 8C. It is supposed to be done. 9A, 9B, and 9C are paper feed units that take out only the uppermost paper from the plurality of papers stacked on the tray moving plates 1A, 1B, and 1C and feed the paper to the transfer unit side, respectively. The sheet feeding units 9A, 9B and 9C are sheet feeding rollers 10A and 10A for pulling out the uppermost sheet which is pressed by the rising of the tray moving plates 1A, 1B and 1C, respectively.
B, 10C and the paper feed rollers 10A, 10B, 10
When two or more sheets are pulled out at C, the separation rollers 11A, 11B, 1 which are frictionally separated and send out only one sheet respectively.
1C and separation lower rollers 12A, 12B, 12C, and each separation upper roller 11A, 11B, 11C and separation lower roller 12
Feed upper rollers 13A, 13B, 13C and feed lower roller 1 for feeding the papers from A, 12B, 12C, respectively.
4A, 14B and 14C. Reference numeral 15 is a toner hopper, and 16 is a developing unit.

Therefore, in such a structure, for example, the uppermost (first) sheet which is in contact with the sheet feeding roller 8A is pulled out by the frictional force with the sheet feeding roller 8A and is separated.
Lower roller 11A, 12A and feed upper / lower roller 13
When the paper is fed out through A and 14A and the paper is fed, the deck upper limit switch 4A is turned from ON to OFF, the energization of the lift motor 2A is started, and the tray moving plate 1A is raised. When the uppermost second sheet due to the rise of the tray moving plate 1A is pressed against the sheet feeding roller 10A, that is, when the upper limit position for sheet feeding is reached, the deck upper limit switch 4A is turned from OFF to ON again. Then, the energization of the lift motor 2A is stopped, the tray moving plate 1A is stopped, and this is repeated every time the sheet is fed thereafter. Then, when the optical sensor 6A detects that the sheets stacked on the tray moving plate 1A are exhausted, that is, when the incident light to the light receiving portion 8A is exhausted, the power supply to the lift motor 2A is started (in this case, The tray moving plate 1A is lowered by the reverse rotation. And
When the deck lower limit switch 5A detects that the tray moving plate 1A has reached the lower limit position for paper supply, that is, when the deck lower limit switch 5A is turned from OFF to ON, the power supply to the lift motor 2A is stopped. Tray moving plate 1A
Is stopped, and the paper can be replenished by pulling out the tray moving plate 1A from the deck.

[0004]

However, since a large amount of paper is consumed by copying in such a deck-feeding type copying machine, the amount of paper dust generated increases accordingly.
Especially when the paper is recycled paper, a large amount of paper dust is generated due to friction separation at each paper feed unit, and the generated paper dust is on the surface of each optical sensor (that is, the surface of the light emitting unit and the light receiving unit). There is a problem that they are attached or accumulated to cause erroneous detection. For example, in the case of an optical sensor that detects the presence or absence of paper, it is erroneously detected that there is no paper even though it is stacked on the tray moving plate, and in the case of an optical sensor that detects a paper jam. There is a possibility that the paper may be erroneously detected as a paper jam even though the paper jam has not occurred.

The present invention has been made in view of the above circumstances, and provides an image forming apparatus in which the cleaning of the optical sensor is automatically performed according to the usage condition without depending on the maintenance. It is intended to be provided.

[0006]

In order to achieve the above-mentioned object, according to the present invention, a plurality of sheets are stacked on a tray moving plate which is moved up and down to feed the sheets, and an optical sensor detects the sheets. In the image forming apparatus configured to perform the above, cleaning means for cleaning the optical sensor which is operated by the tray moving plate is provided, and specifically, the cleaning means is compressed by the lowering of the tray moving plate. The air brush is composed of an air tank for sending air and an air nozzle for blowing the air sent from the air tank to the optical sensor.

[0007]

According to this structure, the air brush is always operated by the tray moving plate that descends when the paper is replenished, and the air from the air nozzle is blown onto the optical sensor to adhere to the surface of the optical sensor. Alternatively, cleaning is performed by blowing away accumulated paper powder, dust, and the like.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment for realizing the present invention will be described below with reference to the drawings. The same parts as those of the conventional one are designated by the same reference numerals and the description thereof will be omitted. In the present embodiment, a cleaning means is provided which is operated by the tray moving plate and cleans the optical sensor with, for example, air. Specifically, as shown in FIG. 1, each tray moving plate 1
Optical sensors 6A, 6B, 6C on the back side of A, 1B, 1C
Air brushes 17A, 17B and 17C are provided in the vicinity, respectively.
7C is abutting plates 18A, 18B, respectively, near the lower limit position when the tray moving plates 1A, 1B, 1C are lowered.
Air tanks 17AA, 17BA, 17CA compressed by the tray moving plates 1A, 1B, 1C that come into contact with 18C and further descend to the lower limit position, and the air sent from each of the air tanks 17AA, 17BA, 17CA. Air nozzles 17AB, 17BB, 17CB for blowing air onto the optical sensors 6A, 6B, 6C respectively
It consists of and.

Therefore, in such a structure, when the optical sensor 6A detects that, for example, the predetermined amount of sheets stacked on the tray moving plate 1A is exhausted, the lift motor 2A is energized to move the tray. The plate 1A descends for replenishing paper, and at that time, the air brush 17A is operated by the contact plate 18A and the tray moving plate 1A from the vicinity of the lower limit position to the lower limit position.
That is, the air tank 17AA is compressed and air is blown from the air nozzle 17AB to the optical sensor 6A. As a result, when the paper is replenished, the paper powder, dust, or the like adhering to or accumulated on the surface of the optical sensor 6A is blown off, and the cleaning is always performed, so that erroneous detection can be prevented.

As described above, in this embodiment, the air brush is operated from the vicinity of the lower limit position of the descending tray moving plate, but it is not necessary to be near the lower limit position, and it is operated by raising the tray moving plate. Is also good. Further, in this embodiment, each tray moving plate is provided with an air brush, but it is provided only on any one tray moving plate, and its air nozzle is branched and extended to be an optical sensor of each tray moving plate. You may make it blow air. Further, although the optical sensor for detecting the presence / absence of the paper on the tray moving plate is cleaned, the present invention is not limited to this, and an optical sensor for detecting a paper jam or the like may be used. Further, an air brush may be provided on the contact plate side instead of the tray moving plate so that the tray moving plate operates.

[0011]

As described above, according to the image forming apparatus of the present invention, air is blown to the optical sensor by, for example, lowering of the tray moving plate. Paper dust, dust, and the like that have adhered to or accumulated on the surface of the sensor can be blown off for sure cleaning, and cleaning according to the user's usage status can be realized without maintenance.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration example in a deck for realizing the present invention.

FIG. 2 is a perspective view showing a main part thereof.

FIG. 3 is a rear view thereof.

FIG. 4 is a side sectional view thereof.

FIG. 5 is a perspective view showing the cleaning state.

FIG. 6 is a diagram showing a configuration example of a conventional deck paper feeding system.

FIG. 7 is a diagram for explaining the detection operation.

[Explanation of symbols]

 1A, 1B, 1C Tray moving plate 6A, 6B, 6C Optical sensor 9A, 9B, 9C Paper feeder 17A, 17B, 17C Air brush 17AA, 17BA, 17CA Air tank 17AB, 17BB, 17CB Air nozzle 18A, 18B, 18C Contact plate

Claims (2)

[Claims] 1. An image forming apparatus in which a plurality of sheets are stacked on a tray moving plate that is moved up and down to feed a sheet, and the sheet is detected by an optical sensor. An image forming apparatus comprising: a cleaning unit that is activated by the cleaning unit to clean an optical sensor. 2. The cleaning means is an air brush comprising an air tank which is compressed by the descending movement of the tray moving plate and sends out air, and an air nozzle which blows the air sent out from the air tank to an optical sensor. The image forming apparatus according to claim 1, wherein: