JPH08292696A - Method for detecting recovered toner quantity in electrophotographic image forming device - Google Patents

Abstract

PURPOSE: To accurately detect recovered toner quantity as much as possible without directly detecting the recovered toner quantity by counting the number and the size of a passing paper and detecting that a toner recovering part becomes full of the toner based on the surface soiling state of the part other than the paper passing part on which a transferring bias is applied. CONSTITUTION: In a plan view development showing the developed surface 50 of the surface of a photoreceptor, the position of a transferring paper 51 which consecutively passes and is electrostatically attracted to a transferring belt and on which an electrostatic image on the photoreceptor is transferred, and a part 52 which is around the transferring paper position and on which surface soiling occurs, for example, when a paper having A5 length (height h2) passes through an A3 length (height h1) paper passing machine, the surface soiling occurs on the part 52 (height h3+h4) outside the transferring paper 51, because the transferring belt is brought into directly contact with the photoreceptor. A paper interval (w) is constant even through any size of the transferring paper is used, and whether the toner recovering part becomes full or not is detected by the recovered toner quantity previously planned by the amount (mg/cm<2> ) of the surface soiling occurring on the part 52.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image recording apparatus such as an electrostatographic copying machine or a laser printer, and more particularly to a toner recovery amount detecting method in these electrophotographic image forming apparatuses.

[0002]

2. Description of the Related Art An example of an electrophotographic image recording apparatus is shown in FIG. Reference numeral 21 in the drawing denotes a transfer belt which is an endless belt, and the photoconductor 1 which is an image carrier rotating in the direction of the arrow in the drawing.
1 is disposed so as to face the photoconductor 1l at a predetermined position. The transfer belt 21 is stretched and supported between one end and a driving roller 22 which is one of a plurality of supporting means and another end which is a driven roller 23 which is one of a plurality of supporting means. Drive roller 22 connected to
Is driven to rotate in the direction of the arrow in the figure. The transfer roller 24, which is a charge applying unit, is connected to a high-voltage power supply, is located downstream of the contact position between the transfer belt 21 and the photoconductor 11, and contacts the back side of the transfer belt 21.
The transfer charge is given to 1. A cleaning blade 28, which is a cleaning unit that cleans the surface of the transfer belt 21, is provided at a position facing the drive roller 22 as a counter in the moving direction of the transfer belt.

The image forming process in such an apparatus will be briefly described. The photoconductor drum 11 is rotationally driven by a motor (not shown) and uniformly charged by the charging device 12, and thereafter, optical writing is performed by image exposure by the optical writing unit 13 to form an electrostatic latent image. This electrostatic latent image is developed by a developing device 14 with a developer containing a predetermined color, for example, black toner, to form a black toner image.

The photoconductor 11 is uniformly charged by the charging device 15 after passing through the developing device 14, and the optical writing unit 1
Optical writing is performed by image exposure by 6 to form an electrostatic latent image. This electrostatic latent image is developed by a developing device 17 with a developer containing a toner of a color different from black to form a toner image of a color different from black. In this way, the two sets of charging devices 12, 15, the optical writing units 13, 16 and the developing device 1
Reference numerals 4 and 17 constitute toner image forming means for forming a toner image on the photoconductor 11, but these toner image forming means may use a pair of charging device, optical writing section and developing device.

The transfer sheet is fed from the sheet feeding device to the registration roller 19, and the registration roller 19 sends out the transfer sheet in accordance with the toner image on the photoconductor 11. The transfer sheet is sent from the registration roller 19 to the transfer belt 21 in which a transfer electric field is generated by the transfer bias applied from the transfer roller 24, and the transfer sheet is transferred to the transfer belt 21.
It is electrostatically attracted to and is transported to the transfer position. At the transfer position, the toner image is electrostatically transferred from the photoconductor 11 to the transfer sheet by the transfer electric field, and then the transfer sheet is separated from the photoconductor 11. The separation claw 25 mechanically separates the transfer sheet that has not been separated from the photoconductor 11 from the photoconductor 11. Then, the transfer sheet is conveyed by the transfer belt 21 and separated from the transfer belt 21 at the driving roller 22. A toner image is fixed on the separated transfer sheet by a fixing device (not shown), and the transfer sheet is discharged to the outside.

The image in the area of the transfer paper and the toner on the background stain are transferred to the transfer paper as they are, and the transfer paper is discharged to the outside of the machine in that state. Outside the transfer paper when a small size paper is passed with respect to the background stain toner adhering to the photoconductor and the maximum paper passing width, for example, when A5 vertical paper is performed on an A3 vertical paper feeder. Since the transfer belt 21 and the photoconductor 11 are in direct contact with each other, 50% of the background stain toner on the photoconductor 11 is directly transferred to the transfer belt. The toner thus transferred to the surface of the transfer belt 21 is scraped off by the cleaning blade 28, and is collected and stored in the collecting container 30 as waste toner.

[0007]

By the way, the recovery container 3
When waste toner is collected to 0, the collection container 30
The toner becomes full and the toner cannot be collected anymore. To avoid this, when the collection container 30 is full, it is replaced with a new empty container or the collection container 30 is replaced.
Maintenance such as discarding the waste toner inside is done. In this case, in order to replace the collection container 30 at an appropriate time, it is necessary to know at a suitable time that the collection container 30 is full of toner. That is, it is necessary to detect the amount of collected toner.

As a method of detecting the amount of collected toner, a method of detecting a pressure change of the collected toner, that is, a waste toner by a voltage change of a piezoelectric element, a method of pushing up a rubber filler or the like by the waste toner pressure and mechanically detecting it, Although a method of detecting the weight change of the toner and the like is known, it is said that since the toner has fluidity, the detection timing may vary depending on how the toner is collected, and thus accurate detection may not be possible. There was a problem. Further, since the sensor is contaminated with the toner, it is necessary to take a treatment for preventing contamination for accurate detection, which causes a problem that the cost of the sensor becomes high. Further, there is a problem that the toner recovery container needs to be larger than necessary due to the large variation, and that a mechanically-detecting container has a problem that the detecting means is attached to increase the cost.

The present invention has been made in view of such conventional problems, and it is possible to directly detect the amount of collected toner without directly detecting the amount of collected toner.
It is an object of the present invention to provide a method capable of detecting a toner recovery amount as accurately as possible.

[0010]

In order to achieve the above-mentioned object, a method for detecting a toner recovery amount in an electrophotographic image forming apparatus according to the present invention includes an electrostatic latent image carrier for holding charged toner, and Charging means for applying an electric charge to the electrostatic latent image carrier and electrostatic latent image forming means for forming an electrostatic latent image corresponding to the original image on the electrostatic latent image carrier to which the electric charge is applied. Developing means for supplying the electrostatic latent image bearing member with charged toner, contact transfer means for transferring the toner image formed by the developing means onto a transfer material, and transfer by the contact transfer means. A transfer material supply unit for supplying the transfer material to the position and a cleaning unit for cleaning the toner remaining on the electrostatic latent image carrier after the transfer are provided, and the transfer unit cleans the toner. Cleaning means for In an image forming apparatus having a toner recovery unit for recovering the cleaned toner, the number of passed sheets and the size of the sheets are counted, and outside the sheet surface at the contact portion between the contact transfer means and the electrostatic latent image carrier. Further, it is characterized in that it is detected that the toner collecting portion is full by a predetermined toner collecting amount due to a background dirt portion of a portion to which the transfer bias is applied.

In the toner recovery amount detecting method in the electrophotographic image forming apparatus according to the present invention, the setting condition of the toner recovery amount can be changed depending on the presence or absence or strength of the pre-transfer charger.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. 2 is a development surface 50 of the surface of the photoconductor 11 as in the apparatus of FIG. 1 and a transfer paper 51 on which the paper is sequentially passed and electrostatically attracted to the transfer belt to transfer the electrostatic image on the photoconductor. FIG. 3 is a plan development view showing a position 52 and a portion 52 around the transfer paper position where background stain occurs.

As described above, the background stain area of the transfer means, which is in contact with the photoconductor, is transferred by the transfer bias, and the toner is collected by the cleaning means in the collecting container or the like. The area (area) between the paper and on both sides greatly changes depending on the paper size, and therefore the amount of toner collected also depends on this. Further, the collection amount changes depending on the presence or absence or strength of the pre-transfer charger, and the paper area also greatly affects the collection amount as shown in FIG.

For example, when A5 portrait (height h2 = 148 mm) paper is fed to an A3 portrait (height h1 = 297 mm) paper machine, a portion 52 (total height h) outside the transfer paper 51 is used.
1-h2 = h3 + h4 = 149 mm), the transfer belt and the photoconductor are in direct contact with each other, so that the background stain occurs. In addition, the transfer paper interval w is 100 mm for any size transfer paper.
And there is 0.0057 mg of background stain on the part 52.
With a device that secures a recovery tank of 100 g / cm ² and a capacity equivalent to 100 g of toner, the amount of background stain per sheet of paper w is

## EQU00001 ## h1.times.w.times.0.0057 = 1.6929 (mg), and the recovery tank is full when only A3 longitudinal paper is used.

[Expression 2] w × 10 ³ /1.6929=59070 (sheets). When the length h5 of the paper is only 21 mm and the length is A5, the background stain amount of the paper interval w and the part outside the paper at the time of passing the sheet are added.

## EQU3 ## h4 × h5 × 0.0057 = 1.78353 (mg), and the amount that the recovery tank is full is

## EQU4 ## w × 10 ³ /1.6929+1.7853=2
It becomes 8765 (sheets).

By calculating the full amount of the recovery tank for transfer papers of other sizes by the same method, the time when the recovery tank is full can be estimated. In addition, the presence or absence of the pre-transfer charger and the strength of the pre-transfer charger can be added to the setting conditions, as the percentage of background stains transferred depends on the presence or absence of the pre-transfer charger. As a result, the accuracy of the toner collection amount is improved.

The above description has been made only for the case of using the transfer belt, but the same applies to the case of using the transfer roller as the transfer means.

[0017]

According to the method for detecting the amount of toner collected in the electrophotographic image forming apparatus according to the first aspect of the present invention, the mechanism can be simplified without providing any detection mechanism in the toner collection container, and at an appropriate time. It is possible to inform that the toner recovery container is full.

The toner recovery amount detecting method in the electrophotographic image forming apparatus according to the second aspect has the same effects as the above.
There is an effect that it is possible to further improve the detection accuracy.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an electrophotographic image recording apparatus.

FIG. 2 is a plan development view showing a position of a transfer sheet that is sequentially passed and a portion where a background stain is generated around the transfer sheet on a surface of a photoreceptor of the apparatus of FIG.

FIG. 3 is a diagram showing a change in the amount of toner collected depending on the presence or absence of a pre-transfer charger and its strength.

[Explanation of symbols]

 50 Development surface of photoconductor surface 51 Transfer paper and its position on photoconductor surface 52 Area where background stain occurs around transfer paper position

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masato Yokoyama 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (2)

[Claims] 1. An electrostatic latent image carrier for holding a charged toner, a charging unit for applying an electric charge to the electrostatic latent image carrier, and the electrostatic latent image carrier to which an electric charge is applied. An electrostatic latent image forming means for forming an electrostatic latent image corresponding to an original image, a developing means for supplying the charged toner to the electrostatic latent image carrier, and a developing means formed by the developing means. Contact transfer means for transferring the toner image to the transfer material, transfer material supply means for supplying the transfer material to the transfer position of the contact transfer means, and toner remaining on the electrostatic latent image carrier after transfer. And a cleaning means for cleaning the
In the image forming apparatus having a cleaning unit for cleaning the toner in the transfer unit and a toner recovery unit for recovering the cleaned toner, the number of passing sheets and the sheet size are counted, and the contact transfer unit is used. Detecting that the toner recovery unit is full by a predetermined toner recovery amount due to a background dirt amount in a portion of the contact surface of the electrostatic latent image bearing member outside the paper surface where a transfer bias is applied. And a method for detecting the amount of toner collected in an electrophotographic image forming apparatus. 2. The toner recovery amount detection method in an electrophotographic image forming apparatus according to claim 1, wherein the setting condition of the toner recovery amount is changed depending on the presence or absence or strength of the pre-transfer charger.