JPS613163A - Abnormality detecting system of electrifier - Google Patents

Abstract

PURPOSE:To detect exactly an abnormality in case an electrifying potential of a body to be electrostatically charged become abnormal, and in case a discharge electrode of an electrifier has been disconnected, etc., by discriminating a fact that a current flowing through a control grid has exceeded a prescribed range, as an abnormality. CONSTITUTION:A current flowing through a grid 1c is detected by a current detector 5 connected in series to a varistor 3, and its detecting signal DA is applied to a comparator 6. The comparator 6 compares the detecting signal DA with a prescribed range, for instance, + or -20% of a value of a normal time, and in case said signal has exceeded this range, an electrifier device abnormality signal EC is outputted to a body control part, etc. of the next stage, and it is informed that an abnormality has been generated in a scorotron electrifier 1. Accordingly, in case a toner adheres to the grid 1c in large quantities and the grid current has become small, and in case an electrode 1a is cut and a discharge current is gone, the detecting signal DA outputted from the current detector 5 becomes small, and the electrifier abnormality signal EC is outputted from the comparator 6. In this way, the body control part displays the generation of an abnormality to the outside, and the device can be set to a stop state as the case may be.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an abnormality detection method for a charger equipped with a control grid.

[Prior art]

Devices that form note copies using the electrostatic electrophotographic process are widely applied not only to copiers but also to printers such as printers, printers such as Redegrinter and LED printers, and printers. In the electrostatic electrophotographic process, after the surface of a photoreceptor is uniformly charged, an electrostatic latent image is formed in correspondence with the recorded image by some means, and this electrostatic latent image is developed with toner. The toner image is transferred to recording paper, and then the toner image on the recording paper is fixed.

In addition, when forming an electrostatic latent image on a photoreceptor, the N7P system (Negative/I-) system) removes the charge from the part corresponding to the recorded image and makes the entire electrostatic latent image a low potential. ,
The P/1) system (I/Positive system) is a method that removes the electric charge of 9 parts in response to the so-called background of people other than the recording artist.
They are called respectively.

Now, a corona charger is used as a means to charge the surface of the photoreceptor, and it is necessary to uniformly charge it to an equal potential of %K! 7I
Therefore, scoro-a chargers, which can control the charging potential, are mainly used.

FIG. 1 illustrates a charging section using one scorotron charger. The photoreceptor in this example is a belt-shaped photoreceptor.

Scorotron charger "l" is a thin wire electrode lax electrode 11
It is composed of a shield case 1b that revolves around L and a control grid IC for controlling the charging potential.A high voltage power supply 2 is supplied to the electrode 1a, and the shield case 1b is grounded, and the control grid IC is grounded via a varistor 3 having a varistor voltage corresponding to the set potential.

Further, the belt photoreceptor 4 is formed by layering a paste material 4as, a conductor 4b, and a dielectric material 4ct as a charge carrier, and the conductor 4b is grounded.

Therefore, ions generated near the electrode la flow to the belt photoreceptor 4, which has a lower potential, and are accumulated on the dielectric member 4C. This accumulation continues until the front position of the belt photoreceptor 40 reaches a set potential corresponding to the varistor voltage of the varistor 3. Further, since the belt photoreceptor 4 moves in the direction of the arrow, the surface of the belt photoreceptor 40 is sequentially charged to the set potential.

The charging state by this scorotron charger IK is expressed isometrically by the circuit shown in FIG. In the figure, J is the scorotron charger source t, FLi is the ion flow equivalent resistance at the grid let, and Ro is the grid.

R7 is the equivalent resistance of the substance attached around the grid IC, R is the ion flow resistance between the grid IC and the belt photoreceptor 4, and R is the equivalent resistance of the substance attached around the grid IC.
rIl is the volume resistance of the dielectric material 4c of the belt photoreceptor 4, and C
rn is the capacitance of the dielectric material 4c of the belt photoreceptor 4, and RB
indicates the resistance to ground of the conductor 4b of the belt photoreceptor 4. Normally, the scorotron charger 1 and the belt photoreceptor 4 are placed close to each other with a gap of 1 to 2 degrees. Also,
Since there is a very high electric field near the electrode 1&, residual toner on the belt photoreceptor 4 and foreign matter in the atmosphere often adhere to the grid 1c.

In particular, when a large amount of high-resistance toner adheres to the grid lc, the resistance RG of #'i in FIG. 2 increases.

Further, the total amount of ions produced by the scorotron charger IK is constant and is generated as a constant current source J as described above.

Therefore, when the resistor RG exerts a large force, the current flowing toward the grid 1c becomes small, so that the current supplied to the belt photoreceptor 4 becomes a large force, and as a result, the surface potential of the belt photoreceptor 4 increases. An example of the relationship between this grid current and surface potential is shown in FIG.

In this way, when the front position of the belt photoreceptor 40 rises,
In particular, in the RU system, the potential of the image area where the electrostatic latent image KI is formed also increases (see FIG. 4).

Next, in the process of developing electrostatic am with toner, the difference between the toner charge and the potential of the electrostatic latent image becomes smaller,
As a result, the contrast of the recorded image decreases, the density decreases, and the sharpness of the image deteriorates.

Furthermore, if an abnormality such as disconnection of the electrode 1a occurs, resulting in poor discharge, there is a problem in that the image quality becomes extremely poor.

〔the purpose〕

The present invention was developed in order to solve the above-mentioned drawbacks of the prior art, and provides a charger abnormality detection method that can detect the occurrence of an abnormality in the charger, such as an electrode disconnection or a high resistance of the control grid. [Structure] In order to achieve the above-mentioned object, the present invention detects the current flowing through the control lead, and determines that the detected value exceeds a predetermined range as an abnormality. There is.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 is a book showing a lid according to an embodiment of the present invention. In this figure, the same parts as in FIG. 1 are given the same reference numerals.

In the figure, a current detector 5 is connected in series with a varistor 3.
The current flowing through grid 1c is detected by , and its detection signal DA is applied to comparator 6.

The comparator 6 compares the detection signal DA with a predetermined range, for example, ±20% of the normal value, and if it exceeds this range, outputs a charger abnormality signal EC to the next stage, such as a main body control section (not shown). This will notify you that a scorotron charger IK error has occurred.

Therefore, when a large amount of toner adheres to the grid IC and the grid current is small, or when the electrode 1a is disconnected and the discharge current disappears, the detection signal DA output from the current detector 5 becomes small. Therefore, the charger abnormality signal EC is output from the comparator 6.

Otherwise, the main body control section may display the occurrence of an abnormality to the outside, and depending on the situation, may cause the device to be brought to a halt.

Incidentally, the detection signal DA't may be outputted directly from the main body control section at an equal pressure. Also, the range in which the detection signal DA is considered to be an appropriate value is the above-mentioned KI\! You may set it as appropriate.

Further, in the above-described embodiment, the potential set by the grid 1eK is given by the varistor voltage of the varistor 3, but the setting is not limited to this, and it can be changed by an energy diode or a DC power supply.

In addition, a belt photoreceptor was used as the object to be charged, but this K1
1IS, a drum-shaped photoreceptor or other recording medium may be used.

〔effect〕

As explained above, according to the present invention, the fact that the current flowing through the control grid exceeds a predetermined range is determined as a total abnormality. This provides the advantage that abnormalities such as disconnection of the electrode can be reliably detected.

[Brief explanation of drawings]

Figure 1 is a configuration diagram illustrating a scorotron charger, Figure 2 is a schematic diagram showing the equivalent circuit of Figure 1, Figure 3 is a graph diagram showing the relationship between surface potential and grid current, and Figure 4 is a diagram illustrating the relationship between surface potential and grid current. The figure is a potential distribution diagram showing an example of potential rise, and FIG. 5 is a diagram showing an apparatus according to an embodiment of the present invention. 1...Scorotron charger, 1&...electrode, 1b...
・Shield case, 1c...grid, 2...high voltage power supply, 3...varistor, 4...bell) ltA light body, 4a...base material, 4b...conductor (layer) , 4
c... Dielectric (layer), 5... Current detector, 6...
Comparator. Figure 2 Figure 3

Claims (1)

[Claims] An abnormality detection method for a charger equipped with a control grid for charging an object to be charged to a predetermined potential includes a current detection means for detecting a current flowing through the control grid, and a detection value of the current detection means is within a predetermined range. An abnormality detection method for a charger that is characterized by determining that an abnormality occurs when the value exceeds the threshold.