JP2002265095A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeding device capable of quickly detecting running out of paper sheet and preventing waste of toner in an image formation device. SOLUTION: A paper sheet vessel or a tray of the paper feeding device 26 and a manually operated paper feeding device 6 provided in the image formation device is provided with a plurality of paper sheet detection sensors 4 in the vicinity of a rear end part of the stored paper sheet. Consequently, when the last paper sheet in the paper sheet vessel is pulled out, the paper sheet detection sensor can detect running out of paper sheet quickly and immediately after a rear end of the paper sheet passes. As a result, image formation operation can be stopped to prevent wasting of toner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus capable of detecting the presence or absence of a sheet at an early stage, thereby preventing waste of toner.

[0002]

2. Description of the Related Art A digital copying machine as an image forming apparatus includes an exposing means for exposing an image on a photosensitive drum surface as an image carrier to form a latent image, a developing means for developing the latent image with toner, and a paper. A transfer unit for transferring the toner, a paper feeding device for supplying the paper to the transfer unit, a fixing unit for fixing the toner to the paper, a paper discharge unit for preparing the paper on which the image is formed in a predetermined state, and the like. Specify the number of copies,
It has an operation display unit for inputting various instructions such as enlargement and reduction of an image.

[0003] The paper feeding device is provided with a plurality of paper containers as paper placement means for storing paper, and each of the paper containers stores paper of a desired size in a predetermined direction.

A manual paper feeder is usually installed on the side of the image forming apparatus, and has a tray serving as a paper placing means also serving as a paper placing table, and places paper on an open tray. The paper is drawn from the tray at the time of image formation and copying is performed.

A paper detection sensor for detecting the presence or absence of paper is provided directly or in the vicinity of each of the above-mentioned paper containers and trays, and when there is no more paper stored or placed, a signal to that effect is controlled. To stop the image forming operation in the digital copying machine.

However, the paper accommodated in the paper container or tray has various sizes, and the orientation of the paper to be accommodated is not fixed. For this reason, conventionally, the paper detection sensor has been installed near the paper container or the drawer opening of the tray so that the paper detection sensor can detect the paper even with the smallest size paper. Alternatively, when the next sheet is pulled out from the paper container or the like, the presence or absence of the sheet is determined by detecting whether there is no more paper to be drawn on the downstream side in the transport direction from the paper container.

[0007]

Therefore, the sheet detection sensor can determine that there is no sheet in the sheet container or on the tray after the last sheet is almost completely fed from the sheet container or the like. Therefore, when it can be determined that there is no sheet, the image forming operation for the sheet next to the last sheet has been started. However, since the next sheet has run out, the image forming operation that has been started is stopped halfway, and the toner image already formed on the photosensitive drum is removed by the cleaning mechanism, and the toner is wasted. Was to be done. In addition, the digital copying machine is in a standby state until the cleaning is completed, causing a wasteful standby time.

An object of the present invention is to solve the above problems. That is, an object of the present invention is to provide an image forming apparatus provided with a paper feeding device capable of preventing waste of toner and waste of time even when paper is exhausted in a paper container or the like.

[0009]

According to the present invention, in order to solve the above-mentioned problems, an image forming apparatus is configured as follows.

That is, (1) an image carrier, exposure means for exposing the image carrier to form an electrostatic latent image, and developing the electrostatic latent image formed on the image carrier with a developer Developing means, transfer means for transferring an image formed on the image carrier onto a sheet, sheet feeding means having a sheet stacking means for storing sheets to be fed to the transfer means, and An image forming apparatus having a fixing unit that fixes the sheet on the sheet, wherein the sheet stacking unit includes a detection unit that detects the presence or absence of the sheet near a rear end portion in a transport direction of the sheet to be placed. An image forming apparatus comprising:

2. The image forming apparatus according to claim 1, wherein a plurality of the detecting units are provided corresponding to a plurality of sizes of sheets.

3. The image forming apparatus according to claim 1, wherein the sheet feeding device is a manual sheet feeding device.

4. The image forming apparatus is a color image forming apparatus using a plurality of color materials.
The image forming apparatus according to claim 1.

5. The image forming apparatus has a plurality of image carriers for each color, and forms a color image by superimposing images of each color formed on the image carrier on an intermediate transfer member. the image forming apparatus of 4, wherein.

6. The image forming apparatus according to claim 5, wherein the intermediate transfer member has a belt shape.

As a result, when the last sheet is pulled out from the sheet container or the tray, it can be immediately detected that the sheet has run out, and the image forming operation is performed before the toner image is formed on the photosensitive drum as the image carrier. Can be stopped, and waste of toner can be prevented.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus having a paper feeder according to the present invention will be described below.

FIG. 4 shows the configuration of the digital copying machine 2 as an image forming apparatus.

The digital copying machine 2 includes a scanner 20
, The control unit 22, the image forming unit 24, and the sheet feeding device 26.
And a fixing unit 28 as a fixing unit, a sheet discharging unit 30 as a sheet discharging unit, a manual sheet feeding device 6, an operation display unit 32 having various input switches, and the like.

The scanner section 20 is installed above the digital copying machine 2 and includes a document feed section 21 and a reading mechanism 8. The reading mechanism 8 includes a stationary original reading unit 34 installed on the right side of FIG. 4 for reading a fixed original, a moving original reading unit 35 installed on the left side for reading an original while reading the original, The movable optical system 9 is configured to be common to both the stationary document reading unit 34 and the moving document reading unit 35.

The optical system 9 includes a lamp 12 and a mirror mechanism 1.
4 and a photoelectric converter 16 such as a CCD for recognizing the reflected light from the mirror mechanism 14. FIG.
The stationary document reading unit 34 includes the lamp 12 and the mirror mechanism 14.
And the moving document reading section 35,
Is shared by two things. In addition, two may be provided.

The original is read as a digital signal,
The read image signal is sent to the control unit 22. In the case of copying, an image signal is sent from the control unit 22 to the image forming unit 24, and an image is formed on the sheet 5 fed from the sheet feeding device 26.

As shown in FIG. 4, the image forming section 24 includes a corona charger 41, a photosensitive drum 42 as an image carrier,
An exposure unit 46 as an exposure unit that exposes the photosensitive drum 42 to form an electrostatic latent image, and a development unit that develops the electrostatic latent image formed on the photosensitive drum 42 with toner as a developer. And a transfer charger 4 serving as a transfer unit for transferring an image formed on the photosensitive drum 42 onto the sheet 5.
9, a separation charger 51, a cleaning unit 50, and the like. The corona charger 41 is, for example, a scorotron charger, and uniformly charges the photosensitive drum 42 to a predetermined voltage, for example, −600 V before the latent image forming process. The photosensitive drum 42 is formed by coating a photosensitive layer on a cylindrical base material made of, for example, aluminum having a diameter of 80 mm, and includes a drive motor for driving the photosensitive drum 42 and an encoder (for detecting the rotational phase of the photosensitive drum 42). (Not shown). The photosensitive layer has a thickness of 1
5-30 μm, dielectric constant 2.0-5.0, and the substrate is grounded. The photosensitive drum 42 is, for example, 280 mm / sec.
The rotation phase of the photosensitive drum 42 is measured and controlled by the encoder. The photosensitive drum 42 is uniformly charged by the corona charger 41 while rotating, and then is exposed by the exposure unit 46 to form an electrostatic latent image on the surface.

The exposure section 46 has a laser, and a laser beam emitted from the laser is reflected by a polygon mirror, and f
The light is irradiated onto the surface of the photosensitive drum 42 via an optical system such as a −θ lens. The polygon mirror rotates at a constant rotation speed, and the main scanning of the laser beam is performed by the rotation, and the sub-scanning is performed by the rotation of the photosensitive drum 42. The formed electrostatic latent image is visualized by the toner in the developing unit 48.

The developing section 48 has a developer therein and forms a magnetic brush. The developer has an average particle size of 8.5 μm, for example.
m of a polyester-based material and an average particle diameter of 60 μm
And the toner concentration is controlled to 4 to 6%.

The toner is transferred from the photosensitive drum 42 onto the sheet 5 by the transfer charger 49. The sheet 5 to which the toner has been transferred is separated from the photosensitive drum 42 by the separation charger 51 and sent to the fixing unit 28 to be fixed.

The transfer charger 49 is installed to face the photosensitive drum 42, and the paper 5
By discharging the electric charges from the back side of the photosensitive drum 42,
Is transferred to the paper 5 electrostatically. The transfer charger 49 is preferably a scorotron discharger, but may be a transfer roller or the like.

The separation charger 51 is a scorotron discharger,
The sheet 5 is composed of a corotron charger, a charging roller, or the like. The sheet 5 adsorbed on the photosensitive drum 42 is neutralized, and the sheet 5 is separated from the photosensitive drum 42.

The cleaning unit 50 has a blade that comes into contact with the photosensitive drum 42, and the toner remaining on the surface of the photosensitive drum 42 without being transferred onto the sheet 5 is scraped off by the blade and collected in the toner box.

Further, the photosensitive drum 42 is controlled by a pre-exposure lamp.
Is erased, and the next print cycle starts. The fixing unit 28 is provided with a fixing device 53, which applies pressure and heat to the paper 5 to which the toner has adhered, and fixes the toner on the paper 5 by welding.

The paper feeding device 26 is provided so as to be able to pull out a plurality of paper containers 3 as paper stacking means, and each paper container 3 stores paper 5 of various sizes. The paper feeding device 26 receives the paper container 3 according to an instruction from the control unit 22 in accordance with an instruction such as the size and orientation of the paper 5 input to the operation display unit 32 or according to the size of a document read by the scanner unit 20. Is selected and the predetermined sheet 5 is fed to the image forming unit 24. In each paper container 3, a plurality of paper detection sensors 4 as detection means for detecting the presence or absence of paper are provided corresponding to paper 5 of various sizes.

The paper detection sensor 4 has a light emitting section and a light receiving section (both not shown) facing the paper 5, and reflects light emitted from the light emitting section to the paper 5 and receives the light at the light receiving section. These are optical sensors, and a plurality of optical sensors are provided in the longitudinal direction of the paper container 3 as shown in FIG. And the paper detection sensor 4
When the size and the orientation of the paper 5 stored in the paper container 3 are input from the operation display unit 32 or the like, the front of the paper container 3 is detected so that the front end and the rear end of the stored paper 5 are sensed. The sheet detection sensor 4 at a position near the rear end of the sheet 5 operates as the detection sensor.

The paper detection sensor 4 is of a type in which a light emitting unit and a light receiving unit are arranged to face each other. The paper detection sensor 4 detects the paper 5 by blocking the light of the paper 5 or a mechanical detection system. A sensor may be used.

The paper discharge unit 30 is a discharge unit that arranges the paper 5 on which an image is formed in a predetermined state and discharges the paper.

The operation display unit 32 is a liquid crystal display device which is provided on the upper surface of the digital copying machine 2 and comprises a touch panel having an input mechanism. Are displayed, and when a finger or the like is pressed on a portion corresponding to the position of the button, a pressure-sensitive pressure sensor made of a transparent electrode (not shown) senses the button, and the button is pressed. Recognize that it has been done.

Next, the paper feeding device 26 of the digital copying machine 2
A specific operation will be described.

The operation display section 32 displays an initial screen when the operation of the digital copying machine 2 is started. The initial screen displays a plurality of buttons, such as a copy start button, a copy number setting, a paper 5 selection button, and a button for instructing enlargement or reduction.

A document is placed on the scanner section 20, and a copy operation start button (not shown) on the operation display section 32 is pressed. Then, the document is fed and the size of the document is read.
The signal of the read size is sent to the control unit 22, and a sheet 5 of a predetermined size is fed from the paper container 3 of the sheet feeding device 26 by the signal from the control unit 22. The operation display unit 3
When the size of the paper 5 is designated from 2, the paper container 3 containing the designated paper 5 is selected, and the paper container 3 is selected.
Is supplied from the printer.

Then, as shown in FIG. 1, the last sheet contained in the sheet container 3 becomes the last sheet, and when the sheet is pulled out, the sheet detecting sensor 4 causes the last sheet 5 to appear as shown in FIG. The control unit 22 detects that the sheet 5 has run out due to the movement of the rear end of the sheet.

Thus, the fact that the paper 5 has run out is
Not only when the sheet 5 is ejected from the sheet container 3 but also when the last sheet is pulled out, it is possible to immediately detect the passage of the rear end of the sheet 5 immediately. Therefore, the process of interrupting the image forming operation of the digital copying machine 2 can be performed early, and an image for the untransmitted sheet 5 is not formed in the image forming unit 24, thereby preventing waste of toner. can do.

Further, such a point becomes remarkable when the image forming apparatus is a color copying machine or the like as a color image forming apparatus. In a color copier, an image is usually formed using red, yellow, cyan, and black toners, and a color image is formed by superimposing each of the images. When this occurs, images formed for all colors are wasted and toner loss is large. Further, in the case of a color copying machine, there is an apparatus in which an image formed on a photosensitive drum of each color is once transferred to an intermediate transfer body, and a color image is formed on a sheet 5 via the intermediate transfer body. In this case, since the image is formed on the photosensitive drum of each color earlier, the effect of stopping the image formation by detecting the absence of the sheet 5 more quickly can be enhanced. The intermediate transfer member for transferring the image of each color may be a cylindrical member, but is preferably in a belt shape, and a remarkable effect can be obtained by applying the present invention.

As described above, the digital copier 2 can detect early that the paper 5 has disappeared from the paper container 3, so that the image forming operation in the digital copier 2 can be stopped promptly, and waste of toner and reduction of standby time. Waste can be prevented.

Although the image forming apparatus is the digital copying machine 2 in the above example, the invention is not limited to this.

Further, the sheet detection sensor 4 is connected to the image forming apparatus 2.
Although the inside of the paper container 3 may be detected from the main body side, it is preferably provided directly on the paper container 3. Also, a plurality of paper detection sensors 4 are installed on the tray 7 of the manual paper feeder 6 where papers 5 of different sizes are frequently used so as to be located near the rear end of the paper 5 to detect the presence or absence of the paper. This is preferable because a remarkable effect can be exhibited. Furthermore,
It is more preferable that both the sheet feeding device 26 and the manual sheet feeding device 6 include the sheet detection sensor 4.

[0045]

According to the image forming apparatus of the present invention, the sheet stacking means of the sheet feeder is provided with the sheet detecting means for detecting the presence or absence of a sheet along the transport direction of a plurality of sheets, so that the last sheet is pulled out. Can detect that the paper has run out, and can detect the absence of paper early,
Thereby, the image forming operation is interrupted, and waste of toner can be prevented.

[Brief description of the drawings]

FIG. 1 is a view showing a paper container provided with a paper detection sensor according to the present invention.

FIG. 2 is a view showing a paper container provided with a paper detection sensor according to the present invention.

FIG. 3 is a view showing a paper container provided with a paper detection sensor according to the present invention.

FIG. 4 is a diagram illustrating an embodiment of an image forming apparatus according to the present invention.

[Explanation of symbols]

 Reference Signs List 2 digital copier 3 paper container 4 paper detection sensor 5 paper 6 manual paper feeder 7 tray 8 reading mechanism 9 optical system 20 scanner unit 21 document transport unit 22 control unit 24 image forming unit 26 paper feeding device 28 fixing unit 30 paper discharge Unit 32 operation display unit 41 charger 42 photosensitive drum 46 exposure unit 48 developing unit 49 transfer charger 50 cleaning unit 51 separation charger 53 fixing unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H027 DC18 DE02 ED16 ED18 EH10 EK03 2H030 AB02 AD05 AD17 BB02 BB42 3F048 AA01 AA02 AB01 BA02 BA07 BA24 BB02 CA03 CA08 CB03 CB05 CC04 DA01 DA02 DB01 DB12 DC14 EB02 CD03 A0301

Claims (6)

[Claims] 1. An image carrier, an exposure unit that exposes the image carrier to form an electrostatic latent image, and a developing unit that visualizes the electrostatic latent image formed on the image carrier with a developer means and a transfer unit that transfers the image formed on the image bearing member onto the sheet, the sheet and the sheet feeding device, a transferred image having a sheet stacking means for storing sheets to be fed to the transfer means An image forming apparatus having a fixing unit that fixes the sheet on the sheet, wherein the sheet stacking unit includes a detecting unit that detects the presence or absence of the sheet near a rear end in a conveying direction of the sheet to be stacked. Characteristic image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the detecting unit includes a plurality of detecting units corresponding to a plurality of sizes of sheets. 3. The image forming apparatus according to claim 1, wherein the sheet feeding device is a manual sheet feeding device. 4. The image forming apparatus according to claim 1, wherein the image forming apparatus is a color image forming apparatus using a plurality of color materials.
The image forming apparatus according to any one of claims 1 to 3. 5. The image forming apparatus has a plurality of image carriers for each color, and forms a color image by superimposing images of each color formed on the image carrier on an intermediate transfer member. The image forming apparatus according to claim 4, wherein: 6. The image forming apparatus according to claim 5, wherein the intermediate transfer member has a belt shape.