JPH09179396A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a precise sure detection by detecting residual toner in a toner supplying part, when a possibility of reaching a toner nearly end is accurately judged. SOLUTION: The densities of a pattern and the surface of a photoreceptor are detected once whenever images are formed by 10 sheets and toner is supplied to obtain a set value when the toner concentration of a developer is proper, so that an image density is adjusted. A toque sensor for detecting torque applied to the shaft of the agitator 16 of the toner supplying part 15 is used as a toner nearly end detecting means, together with an optical density detecting means (P-sensor) and whether the toner of 50g or more for instance remains in a toner hopper or not is judged by whether the output of an agitator torque sensor is on a level or below or not When the toner does not remain, the toner nearly end is displayed on a control display panel. After the display, when the images are formed by 50 sheets, a toner end is displayed and the formation of the images is inhibited. When it is judged that the toner still remains, the forced supply of the toner is continued, without displaying the toner nearly end.

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 using an electrophotographic system, and more particularly to an image forming apparatus for detecting toner near end in a toner replenishing section for replenishing toner to a developing device.

[0002]

2. Description of the Related Art In an image forming apparatus using a two-component developer consisting of toner and carrier, the toner in the developer is consumed as the number of images formed increases, and the toner concentration of the developer in the developing apparatus gradually decreases. As a result, the density of the developed image also decreases. Therefore, the toner concentration of the developer is detected, and when the developer concentration is lower than a predetermined value, the toner is replenished from the toner replenishing portion so that the toner concentration of the developer is always maintained within the predetermined range.
If the toner is repeatedly supplied from the toner replenishing unit, the remaining amount of toner in the toner replenishing unit will eventually reach the bottom, and it becomes necessary to replenish the toner to the toner replenishing unit. In that case, after there is no toner in the toner supply section,
If this is detected and displayed, it is inconvenient to arrange a toner cartridge for toner replenishment, etc., and it is desirable to detect, warn, and display the near end with a margin for forming an image of several tens of sheets.

In an image forming apparatus using a two-component developer,
As a device that detects the near end of the toner replenishment part to the developing device, it detects the torque that rotates the agitator that stirs the toner in the toner replenishment part, and when the remaining amount of toner is low, the resistance generated when rotating the agitator decreases. However, when the torque decreased below a certain value due to the decrease in torque, there was one that was judged as near end and a warning was displayed.
There is a drawback that the detection becomes inaccurate when the toner remaining amount becomes small.

As another method, an optical sensor used in a so-called P sensor method, which is often used as a means for detecting the developer density in order to keep the image density within a certain range, is used. Is the way. The P sensor method is to form an electrostatic latent image pattern of a reference potential by exposing a reference density pattern provided under a side scale of a contact glass on a photoconductor by an exposure science system, or for a fixed time. Scan the photoconductor with a laser beam that repeats blinking at intervals to form an electrostatic latent image pattern of a reference potential, and develop this latent image pattern with a developing device,
A visible image pattern is formed, and its density and the density of the background portion of the photoconductor are detected as a voltage by a photoelectric sensor (referred to as P sensor). This detection is performed once for every 10 copies,
When the voltage for the density of the visible pattern is V _SP and the voltage for the background density is V _SG , if the value of V _SP / V _SG is 1/10 or more, the toner density of the developer is insufficient,
Toner is replenished from the toner replenishing unit to the developing device until V _SP / V _SG exceeds 1/10.

However, when the amount of toner in the toner replenishing unit is very small, the P sensor system cannot replenish a predetermined amount of toner even if a toner replenishing command is issued to the toner replenishing unit. However, since the density of the pattern does not recover within the predetermined range, it is determined that the toner is near the end of the toner replenishing section, and a warning is displayed on the operation plate. However, in the case of this conventional method, the toner near-end detection is judged only by the density of the visible image pattern, so that the toner is actually insufficient when continuously forming images with a high image area ratio or due to potential fluctuations. Although it exists, it is detected as toner near end, and after a predetermined number of sheets, it is displayed as toner end and the machine stops, so that the toner may not be effectively used until the end.

[0006]

SUMMARY OF THE INVENTION In view of the above problems of the electrophotographic image forming apparatus using the conventional two-component developer, the present invention prevents erroneous detection and accurately detects toner near end. An object of the present invention is to provide an image forming apparatus that can effectively use toner to the end.

[0007]

SUMMARY OF THE INVENTION According to the present invention, the above-mentioned problems are caused by optical detection of a visible image pattern density obtained by developing a reference potential latent image pattern formed on a photoconductor by a developing device. In the image forming apparatus having a static detection means and a means for directly detecting the amount of toner remaining in the toner replenishing section for replenishing toner to the developing device, a visible image detected by the optical detection means for each predetermined number of image formations. When the density of the pattern is lower than a predetermined value, the amount of toner remaining is detected by means for directly detecting the amount of remaining toner, and when it is below a predetermined level, it is determined as toner near end, which is solved. It

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a laser beam writing type copying machine according to an embodiment of the present invention. In this embodiment, a reversal development system is used in which a (−) charged organic photoreceptor is used as a photoreceptor and a two-component developer containing a (−) charged toner is used as a developer. The photoconductor drum 1 is rotationally driven by a motor, uniformly charged by a charger 2, and then operated / exposed by a laser beam 3 corresponding to image information in a direction perpendicular to the rotation direction of the photoconductor drum 1. As a result, the electrostatic latent image formed on the photosensitive drum 1 is visualized by the developing device 4. The toner image formed on the photoconductor drum 1 is transferred onto the transfer paper fed from the paper feeding unit 6 under the action of the transfer charger 5, and the transfer paper on which the toner image is transferred is exposed by the separation charger 7. It is separated from the body drum 1, conveyed to a fixing device 8, fixed, and discharged outside the apparatus. The toner remaining on the photoconductor 1 after the transfer is removed by the cleaning unit 9, and the electric charge remaining on the photoconductor 1 is photo-erased by the static elimination lamp 10, and the above steps are repeated again.
In this case, the surface potential of the photosensitive drum 1 is about −800 V in the background portion potential (dark portion potential) V _D , and the image portion potential (light portion potential).
V _L is set to about -50 V, is developed with a potential difference of about -800V to the developing bias potential V _B.

In this image forming apparatus, a P sensor system is used for image density control, a latent image pattern of a reference potential is formed on the photosensitive drum 1 by the above-mentioned means, and is visualized by the developing device 4. As shown in FIG. 2, the visible image pattern 11 is formed on the photosensitive drum 1, and the pattern 11 is formed by the P sensor 14 including the light emitting element 12 and the light receiving element 13.
The detection signal voltage V _SP corresponding to the reflected light from and the detection signal voltage V _SG corresponding to the reflected light from the background portion of the photoconductor are output.

The toner near-end detection control in this embodiment will be described below with reference to the flow chart shown in FIG. The density detection of the pattern 11 and the background of the photoconductor is performed once for every 10 sheets of image formation (S1, S2, S3), and as shown in FIG. 3, the set value V _SG at the time when the toner density of the developer is proper.
= 4V, V _SP ≈0.5 V, that is, V _SP / V _SG = 0.5
The image density is adjusted by replenishing the toner so that the image density becomes /4.0. When V _SG is 2.5 V or less, the sensor is considered to be abnormal (S4), and an instruction to call a service person is given (S5). When the toner concentration of the developer becomes low, V _SP rises above the reference value as shown in FIG.
Since V _SG is unchanged, V _SP / V _SG > 0.5 / 4.0. Even if the toner replenishing operation is performed, the density of the visible image pattern is not recovered and V _SP / V _SG > 0.6 / 4.0 (S
In 7), the toner is not properly supplied to the developer, and it is considered that the toner is near the end of the toner supply portion.

In this embodiment, the toner replenishing section 15 is used as the toner near-end detecting means in combination with the above P sensor.
A torque sensor for detecting the torque applied to the shaft of the agitator 16 is used (S8). FIG. 5 is a curve diagram showing an example of the relationship between the agitator torque represented by the motor load current and the remaining toner amount. In this example, it is determined whether 50 g or more of toner remains in the toner hopper based on whether the output of the agitator torque sensor is below the level (S9),
If it is determined that the toner does not remain, the toner near end is displayed on the operation display plate (S10), and after 50 images have been formed (S11), the toner end is displayed and image formation cannot be performed (S12). When it is determined that the toner remains, the toner near end is not displayed and V _SP / V _SG <
Continue to forcibly replenish toner until it reaches 0.6 / 4.0 (S
13). After V _SP / V _SG <0.6 / 4.0, normal control is performed (return to S1).

In this embodiment, a sensor for detecting the torque applied to the agitator shaft is used as a means for directly detecting the amount of toner remaining in the toner replenishing section for replenishing toner to the developing device. It is also possible to use various known sensors such as detection and volume detection.

[0013]

As described above, according to the image forming apparatus of the present invention, the toner replenishing section for replenishing the toner to the developing device is properly provided when the possibility that the toner near end is reached is accurately determined by the so-called P sensor. Since the remaining toner amount is directly detected, erroneous detection is prevented, and the remaining toner amount is accurately detected to determine that the toner is near the end. Therefore, the toner can be effectively used without being wasted, which is economical. Is.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an overall schematic configuration of a copying machine according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of a visible image pattern density detecting means in the copying machine.

FIG. 3 is a schematic diagram showing set values of a sensor output voltage corresponding to the density of a background portion of a photoconductor and a density of a visible image pattern portion when a toner concentration is appropriate.

FIG. 4 is a similar view when the toner density is low.

FIG. 5 is a curve diagram showing an example of the relationship between the agitator torque of the toner replenishing unit and the remaining amount of toner.

FIG. 6 is a flow chart showing a toner proximity detection control in this embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging charger 3 Writing light beam 4 Developing device 5 Transfer charger 11 Visual image pattern 14 Optical density detection means (P sensor) 15 Toner replenishment section 16 Agitator

[Procedure amendment]

[Submission date] February 4, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

[0007]

SUMMARY OF THE INVENTION According to the present invention, the above-mentioned problem is to detect the pattern detecting means for detecting the visible image pattern formed on the photosensitive member and the toner remaining amount in the toner supplying portion for supplying toner to the developing device. In an image forming apparatus having a remaining amount detecting unit for detecting, when the pattern detecting unit determines that the density of the visible image pattern is low, it is provisionally recognized as toner near end, and the remaining amount detecting unit detects the remaining amount of toner. When the remaining amount is less than or equal to a predetermined amount, the toner near end is set, and when the remaining amount is more than the predetermined amount, the toner is forcibly replenished to solve.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

[0013]

As described above, according to the image forming apparatus of the present invention, when the pattern detecting means accurately determines the possibility that the toner near end is reached, the remaining amount detecting means causes the toner in the toner replenishing portion to be discharged. Since it detects the remaining amount,
The detection by the pattern detection unit and the confirmation of the remaining amount of toner by the remaining amount detection unit are performed, and double toner near end detection is performed. Therefore, erroneous detection by the pattern detection unit due to continuous image formation of an image having a high image area ratio or potential fluctuation can be prevented, and accurate and reliable detection can be performed. Further, since the toner can be used effectively until the end by surely detecting the near end, in the case of the method of replenishing the toner to the toner replenishing section by the toner end, the toner remaining on the inner wall of the toner replenishing section is At the same time, the unused toner in the toner replenishing section can be eliminated without being deposited and fixed on the inner wall. Further, in the case of the method of replacing the toner replenishing portion by the toner end, the toner is not wasted.

Claims (1)

[Claims] 1. An optical detecting means for optically detecting a density of a visible image pattern obtained by developing a reference potential latent image pattern formed on a photoconductor by a developing device, and a toner replenishment for replenishing toner to the developing device. In the image forming apparatus having means for directly detecting the remaining amount of toner in the set, when the density of the visible image pattern detected by the optical detecting means for each predetermined number of images is lower than a predetermined value, the toner remaining amount is The amount of toner is detected by the means that directly detects the amount,
An image forming apparatus, characterized in that it is determined to be near toner end when the level is lower than a predetermined level as compared with a predetermined level.