JPH08179604A - Electrophotographic device - Google Patents

Abstract

PURPOSE: To prevent faulty printing by judging the abnormality of a developing device and generating a specified signal in the case a toner falling detecting means does not detect toner in the midst of printing operation despite the presence of printing dots. CONSTITUTION: The falling toner 13 passes in front of a toner detecting sensor 12 provided at a position opposed to a blade 9. Consecutive pulses are inputted in an integrator from the sensor 12, changed into one pulse in proportion to a toner quantity, and inputted in a CPU. The CPU measures the time of the inputted pulse and estimates the falling toner quantity based on the measured value. Then, the CPU calculates the untransferred toner quantity from relation between the total number of printing dots and transfer rate and compares it with the estimated toner quantity so as to judge whether development is normally performed. In the case of judging it as the abnormality, a signal showing the inhibition of succeeding printing is given to a printing means, and an image controller is informed of the abnormality of development.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus for forming a latent image by scanning a photosensitive member with a laser,
In particular, it is characterized by a means for detecting waste toner falling from the photoconductor in order to monitor whether or not the development is normally performed.

[0002]

2. Description of the Related Art In recent years, a laser beam printer (hereinafter referred to as LBP), which has low noise and high printing speed, has been widely used as an output device of a computer such as CAD. Conventionally, in order to determine whether or not the development is normally performed in the LBP, the user actually makes a determination by looking at the print result, or the amount of toner consumed in the developing device and the amount of waste toner in the waste toner box are determined. It was calculated from the relationship.

[0003]

However, in the above-mentioned conventional device, when the user actually judges,
Since the user has to make a judgment near the LBP, there is a drawback that it is difficult to judge when a large amount of printing is performed at night. Further, in the calculation using the relationship between the toner consumption amount and the waste toner amount, the level cannot be detected by the sensor unless printing is performed on a large number of sheets. There was a problem that it would end up.

The present invention solves the above-mentioned conventional problems, and an object thereof is to make it possible to detect abnormal development immediately by a simple means.

[0005]

To achieve this object, the electrophotographic apparatus of the present invention uses a non-transferred toner image which is not transferred onto a transfer paper among the toner images on the photosensitive member due to regulation by the transfer rate. The toner drop detecting means for detecting the presence / absence of the toner removed by the separating / falling means, and the toner drop detecting means for detecting the presence / absence of the toner removed by the separating / falling means. When the drop detecting means does not detect the toner, it has a signal generating means for judging that the developing device is abnormal and generating a predetermined signal.

[0006]

With the above structure, it is possible to detect whether toner is dropped in the waste toner box and monitor whether or not the development is normally performed. Therefore, it is possible to immediately and automatically detect the development abnormality and prevent the subsequent printing failure. Becomes

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a color LBP according to an embodiment of the present invention, in which 1 is a laser scanner unit (hereinafter referred to as LSU), which is a laser on an endless photoconductor belt 2, that is, a bit image. The optical signal corresponding to the data is scanned. Reference numerals 3-a to 3-d denote developing units, which are supplied with yellow, magenta, cyan, and black toners, respectively, and develop the latent image on the photoconductor belt 2 into toner images. Reference numeral 4 denotes a transfer drum, which superimposes four toner images of respective colors formed on the photoconductor belt 2 into a paper 8
Transfer to. Reference numeral 5 is a fixing device for fixing the toner image transferred onto the sheet 8. Reference numeral 6 denotes a first waste toner box for storing the toner that is not transferred from the photosensitive belt 2 to the transfer drum 4 due to the transfer rate, and stores the toner separated from the photosensitive belt 2 by the blade 9. Reference numeral 7 is a second waste toner box for storing the toner that has not been transferred from the transfer drum 4 to the sheet 8, and stores the toner separated from the transfer drum 4 by the blade 10. Reference numeral 11 is a separation corona charger, 12 is a toner detection sensor provided at a position facing the blade 9, and 13 is toner.

In the electrophotographic apparatus having the above-mentioned components, when the printing operation is started, the photosensitive belt 2 starts to rotate and move at the process speed in the direction indicated by the arrow. The laser emitted from the LSU 1 first forms a latent image for one page of yellow paper on the photoconductor belt 2 while repeating scanning in the direction perpendicular to the moving direction of the photoconductor belt 2. The formed latent image is developed from a position below the yellow developing device 3- (a) to form a yellow toner image, and then is primarily transferred to the transfer drum 4 rotating at the same process speed. The toner 13 that is regulated by the transfer efficiency and is not transferred to the transfer drum 4 is separated from the photoconductor belt 2 by the blade 9 and drops into the first waste toner box 6. The toner 13 falling at this time passes in front of the toner detection sensor 12 provided at a position facing the blade 9.

Thereafter, in the order of magenta, cyan, and black, as in the case of yellow, the developing devices 3-a and 3 are respectively used.
After the latent image is developed into a toner image by -b and 3-c, the toner is superposed and primary-transferred onto the transfer drum 4, and the untransferred toner of each color is the first waste toner box as in the case of yellow. Drop into 6. Transfer drum 4
When a toner image in which four colors are superposed is formed on the upper surface of the transfer drum 4, the toner image on the transfer drum 4 is separated by the separating corona charger 11.
Secondly, the toner image that has been secondarily transferred is fixed to the sheet 8 by the fixing device 5, and the color printing for one page is completed.

Next, the operation will be described with reference to FIGS. 2, 3, and 4. FIG. 2 is a block diagram of an electric section for processing the output of the toner detection sensor 12. The continuous pulse is input from the toner detection sensor 12 to the integrator 14 and converted into one pulse proportional to the toner amount, and then the CPU 15 outputs the pulse. Is entered. The CPU 15 measures the time of the input pulse,
The amount of dropped toner is estimated from the measured value. CPU
Reference numeral 15 calculates the amount of toner that is not transferred from the relationship between the total number of printed dots and the transfer rate, and compares it with the estimated amount of toner to determine whether or not development is normally performed. If it is determined to be abnormal, the printing unit 17 To the image controller 16 and to notify the image controller 16 of a developing device abnormality. Reference numeral 18 in the drawing is a ROM for giving a memory signal to the CPU 15.

FIG. 3 is a diagram showing a continuous pulse from the detection sensor 12 and a signal obtained by integrating the pulse when the total number of printed dots is the same. The signal (a) is the output from the toner detection sensor 12 when the developing device operates normally, and the pulses for detecting the individual toner particles are continuous pulses, and the continuous pulse is output by the integrator 14. The integrated result is the signal (b). Further, the signal (c) is the toner detection sensor 12 when the developing device operates abnormally.
The pulse for detecting the individual toner particles is a sparse pulse, and the result of integrating the continuous pulse by the integrator 14 is the signal (d).

FIG. 4 is a graph of a toner amount comparison data table calculated from the total number of print dots used by the CPU 15, and this table is used to determine the case of each of the pulse widths T1 and T2. This data table can be easily created by previously measuring the toner amount corresponding to the pulse width obtained by integrating the output of the toner detection sensor 12. In FIG. 4, the estimated value range of the untransferred toner amount in the number of print dots at this time is set to h, and when the pulse width is T1, it is OK, but when the pulse width is T2, it can be determined that it is NG.

The determination by the CPU 15 is performed for each color,
Even if only one color is abnormal, the abnormality can be accurately detected, so that subsequent printing can be prohibited and defective printing can be prevented. Although the abnormality has been described using the color LBP as an example, the monochrome L
It is obvious that the case of BP can be detected in the same manner.

[0014]

As is apparent from the above description of the embodiments, the present invention can detect whether toner is dropped in the waste toner box and monitor whether the development is normally performed. However, development abnormalities can be immediately and automatically detected, and subsequent printing defects can be prevented.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of an electric section that processes an output of a toner detection sensor of the electrophotographic apparatus.

FIG. 3 is a signal diagram of the electric block.

FIG. 4 is a graph of a table for determining the output of the toner detection sensor of the embodiment.

[Explanation of symbols]

 1 Laser Scanner Unit (LSU) 2 Photoconductor Belt 3 Developing Device 4 Transfer Drum 5 Fixing Device 6 First Waste Toner Box 7 Second Waste Toner Box 8 Paper 9 Blade 10 Blade 11 Separation Corona Charger 12 Toner Detection Sensor 13 toner

Claims (1)

[Claims] 1. An electrostatic latent image formed by scanning a photoconductor with an optical signal modulated according to bit image data is developed by a developing device into a toner image, and the toner image is transferred by corona discharge. An electrophotographic apparatus for transferring a toner image on a transfer paper to a transfer paper and fixing the toner image on the transfer paper, wherein a non-transferred toner image that is not transferred to the transfer paper due to a transfer rate regulation is selected from among the toner images on the photoconductor. The device further includes a unit for separating and dropping the photoconductor, and a toner drop detecting unit for detecting the presence or absence of toner removed by the unit for separating and dropping, and even if a print dot exists in the bit image data. Regardless, during the printing operation, when the toner drop detecting means does not detect the toner, it is determined that the developing device is abnormal and a signal generating means for generating a predetermined signal is provided. Child photography device.