JPH02187783A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent deterioration of image definition or damage to a photosensitive body by putting out a warning to the photosensitive body when the weight of developer inside the container exceeds a specified value before reaching a specified value in volume. CONSTITUTION:After transferring with toner, the developer retained on the photosensitive drum is eliminated by a cleaning device, retained charge is erased by an eraser, and accepted by a recovering container, On the other hand, a developer weight detecting device 6 and developer volume detecting device 7 are included in a controlling circuit with computer CPU 1 as the main body. The volume and weight of the recovered developer is detected by the detecting devices 6 and 7. Whether the weight specified beforehand has been reached or not, before the value of detecting device 7 reaches the beforehand specified volume, is judged by the CPU 1. Thus, when the above weight is reached, a warning displaying device 8 carries out a carrier adhering warning. Deterioration of image definition and damage to the photosensitive body due to adhering of carrier to the photosensitive drum can be prevented beforehand.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus such as an electrophotographic copying machine or a printer.

[Prior Art] This type of image forming apparatus performs image exposure on the photoreceptor drum to form an electrostatic latent image on the photoreceptor drum, and develops the latent image with a developing device. The transferred toner image is transferred to the transfer +J and fixed.

The developing method includes a one-component developing method in which the developer includes only a developing toner, and a two-component developing method in which the developer includes toner and carrier particles.

Among these, in the two-component development method, toner is mixed with carrier particles, triboelectrically charged and attached to the carrier, and the carrier is transferred together with the toner onto an electrostatic latent image surface on a photoreceptor using a developing sleeve that usually has a built-in magnet. This is a development method widely used today in which the toner is transferred to the latent image and deposited on the latent image.

[Problem to be solved by the invention]

According to this two-component development method, only toner is originally attached to the photoreceptor, but carrier may also be attached to the photoreceptor for various reasons.

Causes of carrier adhesion to the photoconductor include: ■ Incorrect mechanical settings in the developing device; ■ Abnormality in the developing via non-voltage; ■ Defective developer; ■ Abnormality in the image forming sequence; ■ Abnormality in the photoconductor potential. is possible.

In any case, if carrier adheres to the photoreceptor, the carrier in the developer is consumed in this way, resulting in a decrease in the toner conveying force on the developing sleeve and abnormal charging of the toner, which can cause various image problems. occurs. Furthermore, the carrier is pinched by a cleaning device that removes residual toner on the photoreceptor, damaging the photoreceptor.

However, no suitable means for solving such problems has been found so far.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an image forming apparatus that can prevent deterioration in image quality and damage to the photoreceptor caused by adhesion of the carrier in the developer to the photoreceptor.

[Means for Solving the Problems] As a result of research, the present inventor found that the specific gravity of the carrier and toner in a two-component developer is usually considerably larger. ~4 times, and about 3 to 8 times in terms of bulk specific gravity.We focused on the fact that as the amount of carrier attached to the photoreceptor increases, the specific gravity of the entire developer removed from the photoreceptor by the cleaning device increases accordingly.
This led to the completion of the present invention.

That is, in the present invention, a photoreceptor is imagewise exposed to form an electrostatic latent image on the photoreceptor, the latent image is developed with a two-component developer containing toner and a carrier, and the resulting toner image is In an image forming apparatus in which the developer is transferred to a transfer material and fixed, and residual developer on the photoreceptor is removed by a cleaning device, a container for collecting the developer removed from the surface of the photoreceptor by the cleaning device, and a developer in the container. a device that detects the volume of the developer in the container, a device that detects the weight of the developer in the container, and a device that detects the weight of the developer in the container, and reaches a predetermined weight before the developer in the container reaches a predetermined volume based on information from both of the detection devices. The present invention provides an image forming apparatus characterized in that it is equipped with a means for determining whether or not the carrier has reached the weight, and issuing a carrier adhesion warning when the weight reaches the weight.

Examples of the volume detection device include one that can continuously detect the volume of the developer accumulated in the container, one that can detect whether a predetermined volume has been reached, and one that can detect whether a predetermined volume has been reached. It is conceivable to have something that can detect whether each of these has been reached.

The weight detection device may be one that can continuously detect the weight of the developer accumulated in the container, one that can detect whether a predetermined weight has been reached, or one that can detect whether a predetermined weight has been reached. A device that can detect whether each weight has been reached is conceivable.

[For production]

According to the image forming apparatus of the present invention, the residual developer removed from the photoreceptor drum by the cleaning device is collected in the collection container. When the developer in the container reaches a predetermined volume, it is detected by a volume detection device. When the weight of the developer in the container reaches a predetermined weight, it is detected by a weight detection device. However, if the developer in the container reaches the predetermined weight before reaching the predetermined volume,
The warning means issues a warning indicating abnormal adhesion of carrier to the photoreceptor.

〔Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows the internal structure of a copying machine which is an embodiment of the present invention.

This copying machine is equipped with a photosensitive drum 1 in the center, and around the drum 1 there is a charger 11 and a developing device 12.
, a transfer/separation charge jug 13, a blade type cleaning device 14, and an eraser 15 in this order.

An optical system 2 is provided above the photosensitive drum 1.

The optical system illuminates the original on the original table glass 21 with an illumination lamp 22.
and a first mirror 23. The original image is transferred from the first mirror 23 to the second and third mirrors.
The image is projected onto the photosensitive drum 1 via the mirrors 24 and 25, the lens 26, and the fourth mirror 27.

The photoreceptor drum 1 is moved in the direction of arrow a in the figure by a driving means (not shown).
After being rotationally driven in the direction and uniformly charged by the charger 11, it receives image exposure from the optical system 2, and an electrostatic latent image corresponding to the original image is formed.

The latent image is developed by a developing device 12. Developing device 1
2 is based on a two-component development system, and contains a developer (2) consisting of a toner with a bulk specific gravity of 0.3 and a fibrocarrier with a bulk specific gravity of 2.4.

On the upper left side of the photosensitive drum 10 are paper feed cassettes 31 and 32.
is arranged, and the paper in the cassette 31 is fed to the paper feed roller 3.
3 and sent to the timing roller 35 via the intermediate feed roller 34.

The paper in the cassette 32 is pulled out by a paper feed roller 36 and sent to a timing roller 35 via an intermediate feed roller 37.

The paper supplied from the cassette 31 or 32 and reaching the timing roller 35 is timed with the arrival of the toner image on the photoreceptor drum 1, and is sent to the transfer section.

After the toner image is transferred to the paper sent to the transfer section by the transfer/separation charger 13, it is separated from the drum 1.
The sheet is sent to a fixing device 42 by a transport heald 41, where the toner image is fixed, and then ejected to a paper ejection tray 44 by a paper ejection roller 43.

After the toner image is transferred, the developer remaining on the photoreceptor drum 1 is removed by a cleaning device 14, and then the residual charge on the surface of the photoreceptor is erased by an eraser 15.

Now, the cleaning device 14 is equipped with a developer discharge device 141 including a coil spring rotationally driven by a drive means (not shown), and the developer discharged from the cleaning device 14 by the discharge device 141 is collected in a collection container. Uke is accepted in 5.

The container 5 is placed on a plate 6J, as shown in FIG. Habane 6
2, it is suspended from the main body frame of the copying machine.

The other end of the plate 6]2 is provided with a claw 63, which is rotatably connected to the main body frame of the copying machine and is connected to an arm 65 which is lifted upward by a spring 64.
It is placed in a position where it engages. A microswitch 66 is arranged below the arm 65.

These plate body 61, spring 62, pawl 63, spring 64, arm 65, and microswitch 66 constitute a device 6 (see FIG. 4, which will be described later) for detecting the weight of the developer in the container 5. The detection device 6 generates a signal indicating that a predetermined weight of developer is present in the container 5 when the microswitch 66 is turned on.

That is, when the developer in the container 5 reaches a predetermined weight, the plate 61 rotates downward against the spring 62 due to the weight, and the claw 63 lowers the arm 65 against the spring 64. ,
This activates the microswitch 66.

Further, as shown in FIG. 2, at least a portion 51 of one end of the container 5 is formed transparently, and this transparent portion 5
A light emitting element 71 made of a light emitting diode and a light receiving element 72 made of CdS are arranged with the light emitting element 71 in between. These elements 7 and 72 are shielded from light when a predetermined volume of developer has accumulated in the container 5, and the volume is thereby detected. These elements 71 and 72 are members of the developer volume detection device 7 (see FIG. 4). The device 7 is shielded from light by the developer between elements 71, 72, and when element 72 is turned off, it emits a signal indicating that there is a predetermined volume of developer in the container 5.

In this embodiment, the predetermined volume is the volume at which the container 5 is exactly full of developer and the developer must be thrown away or the container replaced. be.

Further, the predetermined weight of the developer in the container 5 is determined by the fact that microcarriers in the developer abnormally adhere to the photoreceptor drum 1 in the developing device 12 and the specific gravity of the developer removed by the cleaning device increases. When the vehicle gap is detected at Rtl when the volume of the developer in the container 5 reaches the predetermined volume, it means that the specific gravity of the developer has increased from the normal state, and therefore the microcarrier This value indicates the number of abnormalities occurring. In this example,
The weight is approximately 1 to 2 times higher than the normal weight when the container is full (approximately 1000 cc).

FIG. 4 shows the control circuit. This control circuit detects the volume and weight of the developer in the container 5, and detects the volume and weight of the developer in the container 5.
When the container becomes full, a full display is displayed, and if the predetermined weight is reached before the container becomes full, a warning of carrier adhesion abnormality is issued.

This control circuit is centered around a microcomputer CPU1, and a weight detection device 6 and a volume detection device 7 are connected to its input terminals.

A warning indicator 8 made of, for example, a light emitting diode is connected to the output terminal, and a full indicator F, made of a light emitting diode, for example, is connected to indicate when the container is full of developer. In addition, Microcomputer 4-Event C
The PUI communicates with the microcomputer CPU (not shown) by an interrupt from the microcomputer CPU, which controls the entire operation of the copying machine.

The operation of the microcomputer CPU 1 is as shown in the flowchart of FIG.

Initial settings are performed in step #l, and device 7 is configured in step #2.
Check whether the developer is full or not. At the time of detection, that is, when the element 72 is shielded from light, the full indicator F is displayed in step #3.
Turn on the light and return to step #2. If it is not full in step #2, the process proceeds to step #4, where it is checked whether the weight has reached a predetermined weight. If it has been reached, the warning indicator 8 is turned on in step #5 and the process returns to step #2; if it has not been reached, the process directly returns to step #2.

In place of the container 5 and the detection device 6.7, the means shown in FIG. 6 can be employed.

That is, the developer discharged from the cleaning device 14 by the developer discharge book hanging device 141 is transferred to the transparent container 5.
The optical sensor SE and the light emitting diode (81
,91), (82,92), (83,93), (84
, 94), (85, 95), and when a predetermined volume v1, ■2, ■3, ■4, V5 is accumulated in the container 50, it can be detected. These sensors SE constitute a volume detection device 90 (see FIG. 8, which will be explained later), and when these sensors SE are shielded from light, the volume
A signal indicating that 1 to 5 has been reached is output. Incidentally, the volume V5 is the volume at which the container 5 is full of developer and the developer is thrown away, but the container must be replaced.

Further, the lower surface of the container 50 is supported by the load cell 10, and each time the load cell output reaches a predetermined output W1, W2, W3, W4, in other words, each time the developer in the container reaches a predetermined weight, It is determined whether or not the optical sensor SE is shielded from light, and thereby it is determined whether a volume of developer corresponding to the weight is accumulated in the container 50. If the volume corresponding to the weight has not been reached, the carrier is removed. If abnormal contamination is detected, a warning will be issued. The load cell 10 is a weight detection bag N
LOW (see FIG. 8), the detection device outputs a signal indicating this each time the developer in the container reaches a predetermined weight W1 to W4.

FIG. 9 shows the relationship between the 1:J-tocell output W and the developer volume in the container, and the solid line in FIG.
It shows the relationship between the load cell output W and the volume of the developer in the container when the developer collected at No. 0 is normal and free of abnormal microcarriers. In this relationship, the developer volumes ■1, ■2, v3, v4 corresponding to the respective load cell outputs WLW2, W3, and W4 to be detected are the volumes ■1, ■2, and ■3 detected by the volume detection device 90. , ■It is a value higher than 4. Therefore, as shown by the dashed line in FIG. 9, for example, when the load cell output is W3, the volume is
If V2O is lower than 3, it means that the specific gravity of the developer is higher than in the normal case, that is, there is abnormal contamination of carrier.

FIG. 8 employs the device shown in FIG. 6 to warn of abnormal adhesion of microcarriers to the photoreceptor tram 1, and also warns of abnormal adhesion of microcarriers to the photosensitive tram 1.
2 shows a control circuit for notifying that the developer is full.

This control circuit is centered around a microcomputer CPU2, and the weight detection device 100 and the volume detection device 90 are connected to its input terminals. A warning indicator 8 made of a light emitting diode, for example, and a developer full indicator F are connected to the output terminal. Further, the microcomputer CP [J2 is a microcomputer CI (not shown) that controls the operation of the entire copying machine.
) Communicate with the microcomputer using interrupts from U.

The operation of the microcomputer CPU2 is as shown in the flowchart of FIG.

First, in step #l, initial settings are performed, and in step #2, it is checked whether the optical sensor SE85 of the device 90 detects that the developer is full. If the full state is detected, the full state indicator F is turned on in step #3 and turned gray in step #2.

If it is not full in step #2, check whether the developer weight is W4. When W4, it is checked in step #5 whether the developer volume is v4. ■If it is 4, the warning indicator 8 is turned on. ■If not 4 (when SE84 is on), return to step #2. If W4 is not detected in step #4, it is determined whether the weight is W3 in step #7. Thereafter, in the same way, U7 executes the step gaff and subsequent steps.

When the volume detection sensors are arranged in multiple stages as shown in FIG. 6, the developer weight at that time is checked every time the developer volume reaches (1) to (5). A warning may be issued if the normal value is exceeded. Also, each time the developer volume reaches (1) to (5), the developer weight at that time is checked, and a warning is issued if the difference between this weight and the previously detected weight exceeds a predetermined value. Good too.

As explained above, according to the embodiment of the present invention, when microcarriers are abnormally attached to the photoreceptor tram 1 in the developing device 12, the specific gravity of the developer removed from the photoreceptor surface in the cleaning device 14 increases. As a result, abnormalities can be easily discovered, and deterioration in image quality and damage to the photoreceptor drum caused by abnormal adhesion of carrier to the photoreceptor drum can be prevented.

The present invention is not limited to the above embodiments, and can be implemented in various other ways. For example, a sensor of a different type from the transmission type photosensor shown in the above embodiment may be used as the volume detection device. In the embodiment described above, a warning is displayed when abnormal adhesion of microcarriers occurs, but instead of this, or together with this, the copying machine may be automatically stopped.

Incidentally, although the above embodiment has been described with respect to a copying machine, the present invention can also be applied to a printer or the like.

〔Effect of the invention〕

According to the present invention, an electrostatic latent image is formed on the photoreceptor by imagewise exposure on the photoreceptor, and the latent image is developed with a two-component developer containing an I/toner and a carrier, and a toner image obtained is obtained. In image forming apparatuses, in which the image is transferred to a transfer material, fixed, and residual developer on the photoreceptor is removed by a cleaning device, the image quality is degraded and the carrier in the developer adheres to the photoreceptor. Damage to the photoreceptor can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a diagram schematically showing the internal structure of a copying machine which is an embodiment of the present invention, Fig. 2 is an explanatory diagram of a developer volume detection device in the developer collection container, and Fig. 3 is an illustration of the inside of the collection container. Part 4 is a block circuit diagram of microcarrier abnormal adhesion warning display control, Figure 5 is a flowchart showing the operation of the microcomputer shown in Figure 4, and Part 6 is an explanatory diagram of the developer weight detection device.
The figure shows another example of a device that detects the volume and weight of the developer in the collection container. Figure 7 is a graph showing the relationship between the load cell output and the volume of developer in the container. Figure 8 is a warning for abnormal adhesion of microcarriers. The block circuit diagram of display control, FIG. 9, is a flowchart showing the operation of the microcomputer shown in FIG. DESCRIPTION OF SYMBOLS 1... On photoreceptor, 12... Developing device, 14... Cleaning device, 5.50... Collection container, 6.100... Developer weight detection device, 7.90...
Developer volume detection device, 8...Warning indicator, F...Full indicator, CPUI, CPIJ2...Microcomputer. Applicant: Minolta Camera Co., Ltd. (↓Σ/D

Claims (1)

[Claims] (1) Imagewise exposing a photoreceptor to form an electrostatic latent image on the photoreceptor, developing the latent image with a two-component developer containing toner and carrier, and transferring the resulting toner image to a transfer material. In an image forming apparatus in which the developer is transferred and fixed, and residual developer on the photoreceptor is removed by a cleaning device, there is provided a container for collecting the developer removed from the surface of the photoreceptor by the cleaning device, and a volume of the developer in the container. a device for detecting the weight of the developer in the container, a device for detecting the weight of the developer in the container, and whether or not the developer in the container reaches a predetermined weight before reaching a predetermined volume based on information from both of the detection devices. An image forming apparatus characterized in that the image forming apparatus is provided with means for determining whether the carrier weight reaches the weight limit and issuing a carrier adhesion warning when the weight reaches the weight limit.