JPS5974570A - Picture quality controlling method of electrostatic recording system - Google Patents

Abstract

PURPOSE:To eliminate easily a pattern image formed in a detection area, by setting the electrostatic charge potential of an electrostatically charged pattern formed in the detection area to a value lower than an electrostatic latent image formation potential by one level with respect to absolute value. CONSTITUTION:The discharge voltage of a charger 2 is switched to two stages, and first, the detection area is electrostatically charged uniformly up to an electrostatically charged pattern electrostatically charged potential VP, and next, electrostatically charged voltage is raised to an electrostatic latent image formation potential V1. The timing of the exposure start due to an exposure luminous flux 4 to the detection area is adjusted as shown in Fig. II in accordance with this discharge voltage to attain an electrostatically charged pattern shown in Fig. III. In an electrostatic latent image formation area, an electrostatic latent image is formed by the exposure due to the exposure luminous flux. It is indicated by a broken line in Fig. III. The electrostatically charged potential of the electrostatically charged pattern is set to a value lower than the electrostatic latent image formation potential by one level to facilitate cleaning the pattern picture, thereby controlling property the picture quality.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image quality control method in an electrostatic recording system.

In this specification, the term "electrostatic recording method" refers to an electrostatic recording method in which an electrostatic latent image is formed on a photoconductive latent image carrier by charging and snoring light, and this electrostatic a-image is developed. The so-called electrophotographic recording method transfers a visual image onto a recording sheet, and the electrostatic latent image is formed by position-selectively charging a dielectric latent image carrier using a multi-needle electrode or the like. Electrostatic latent image, image,
A general term for a recording method in which a visible image is transferred onto a recording sheet.

Electrophotographic recording systems are well known in connection with electrophotographic copying houses, etc., and recording systems using dielectric latent image carriers have been proposed for application to facsimile receiving devices, various printers, etc. I'm here.

By the way, in such an electrostatic recording method, a detection area is formed outside the electrostatic latent image forming area of the latent image carrier,
A predetermined charging pattern is formed in this detection area during recording, this charging pattern is clearly imaged to obtain a pattern image of toner, the density of this pattern image is detected, and based on the detection result, the developing device There are known methods for controlling the quality of electrostatically recorded images by replenishing toner, controlling the developing bias voltage, controlling the amount of exposure light, etc.

That is, it corresponds to the toner density in the developing device and the formation of a pattern image obtained by clearly imaging the charged butter ν formed in the detection area.

Therefore, the toner density can be known from the density of the pattern image, and the quality of the electrostatically recorded image can be controlled by correcting the toner or controlling the image bias voltage.

This image quality control method can be implemented regardless of whether the printing method is wet or dry.

Conventionally, such image quality control methods have had the following problems.

That is, when implementing this control method, the pattern image formed in the upper region of the latent image carrier cannot be transferred onto the recording note. This is because, if transferred, this pattern image will appear on the recording sheet, making the recorded image unsightly.

Furthermore, transferring a visible image onto a recording sheet means repeatedly using the same latent image carrier.
Since the image quality control has to be performed repeatedly 7 times, the cross-turn image formed in the detection area must also be removed from the latent image carrier 7 times per recording process.

Removal of this putter 7 image is carried out using a latent image carrier IJ-Ninog device.

By the way, in the conventional method, the charging potential of the charging pattern formed in the detection area is the same as the potential of the electrostatic latent image Y, and therefore, if there is sufficient toner in the imaging device, , the toner that forms the turf image is quite dense, and when the turf image is removed from the image carrier by the cleaning device, the cleaning conditions that cannot be imposed on the cleaning device are harsh. ,
In other words, cleaning of the pattern image tends to be defective, and due to kneading, proper image hook control cannot be performed.

An object of the present invention is to improve the above-mentioned image quality control method in order to solve such problems.

See the drawing below! The present invention will be explained based on specific examples.

In FIG. 211, reference numeral J indicates a photoreceptor which is a photoconductive latent image carrier. 2 is a charger, 3 is an erase lamp, 4 is an exposure light beam, 5 is a developing device, 6 is a detection system, 7 is a transfer charger, 8 is a cleaning device, 9 is a static eliminator, and S is a A record sheet is shown in detail.

In this setup, the electrostatic recording process is performed roughly as follows.

That is, during recording, the m4 light body l rotates in the direction of the arrow, that is, counterclockwise in the figure. The charger 2 uniformly charges the circumferential surface of the photoreceptor 1, and the loose lamp 3 eliminates the charge in unnecessary portions by irradiating light.

Then, the image is illuminated by the exposure light beam 4.

The knee light beam 4 may be an imaging light beam that forms an optical image of the document, or a laser beam that scans the photoreceptor J in a line in the direction of the rotation axis while turning on and off in accordance with a recording signal.

The electrostatic latent image formed by the image lightning is developed by the developing device 5, and the resulting visible image is transferred onto the recording sheet S by the transfer charger 7. Developing device 5 is a dry developing device or a wet printing device.

It can be an image device. In addition, the record/resort S is generally plain paper.

The h1 recorder S that did not transfer the visible image is fixed,
Alternatively, it may be discharged outside the device without undergoing necessary processing such as drying.

After the visible image has been transferred to the photoreceptor 1, the static electricity is removed by a cleaning device 8, a cleaning device 1, and a static eliminator 9. Thus, the recording process ends.

Now, a detection head Jl is set outside the tip of the electrostatic latent image forming area of the photoconductor J serving as the latent image carrier. This state is conceptually shown in Figure 2. Arrow A indicates the direction of movement of the photoconductor circular surface due to the rotation of the photoconductor 10, and
is a detection area, and the area D2 is an electrostatic latent image forming area.

However, in the case of a seamless, endless photoreceptor, the tip of the electrostatic latent image forming area, that is, the boundary between areas DI and D2, is generally fixed on the photoreceptor ('
l°Not there. Therefore, even though the detection area is set outside the tip of the electrostatic latent image forming axis area, the area outside the tip of the electrostatic latent image area 1 is used as the detection area. Therefore, the detection area does not necessarily need to be fixedly set at a specific position on the photoreceptor.

Now, a charging pattern P as shown in the figure is formed in the detection region DJ (Figs. 2 and 2). This charging pattern P is visualized by the imaging device 5, and the density of the image I# is detected by the detection system 6 (Fig. 1).
Lol.

The detection system 6 includes a light receiving element 62 of the light source 61 and a light source 6.
The light from J is irradiated onto the peripheral surface of the photoreceptor, and the reflected light is photoelectrically converted by the light receiving element 62. The surface of the latent image carrier, whether light-conducting or dielectric, has a reflectance of -W, but if there is toner on the optical surface, the toner will cause the light source 6 to have a reflectance of -W. is absorbed, so the reflectance decreases.

By the way, if the charging pattern/P shown in Fig. 2 is uniformly charged, the output of the light receiving element 6 of the image of butter 7 due to this charging pattern P will be as shown in Fig. 3. 7'I-There will be. When the pattern image area is irradiated with light from the light source 6, one reflected light becomes small due to light absorption by the toner, and the output voltage of the light receiving element 62 becomes a low value of vl.

An increase in the output voltage v1 means that the reflected light is weak, that is, the density of the butter 7 images is low, or in other words, the amount of toner in the image device 5 is reduced. Therefore, by replenishing toner every time the output voltage V1 exceeds a predetermined set potential Vo, the surface quality of the electrostatically recorded image can be well controlled.

By the way, as mentioned above, if the charging potential of the charging pattern formed in the detection area is the same as the electrostatic latent image forming potential, cleaning failure of the pattern image will occur, and proper 1ihi image quality η control will occur. I can't do it anymore.

Therefore, in the present invention, the charging potential of the charging pattern is set one step lower than the electrostatic latent image forming potential to facilitate cleaning of the pattern image, thereby solving the above problem and controlling the proper image quality. I made it possible to do so.

For this reason, the density of the pattern image obtained from the charging pattern 7 is approximately a so-called intermediate density even in a normal case, but even in this case, the state of the presence of toner in the developing device can be sufficiently detected, and the image quality There is no problem with the control and the book.

By the way, as a method for forming a charged pattern in the detection area, a method of uniformly charging the detection area and then irradiating a light image of the charged pattern with the negative putter 7 may be considered, but the density of the negative pattern and the intensity of the illumination light may vary. It is unthinkable that the charge pattern tends to change over time, and that the charging pattern also changes over time, causing problems in image quality control.

In the embodiment shown in Fig. 1, taking such points into consideration, a charged pattern is formed using a negative pattern of light fJ [irradiation]. Such a method is
There are many different types, but here I will give three examples.

4. By the method shown in Figure 4 (A), first, the discharge voltage of the charter 2 is switched in two stages, and the detection area is uniformly charged to the charging pattern charging potential Vp, and then the electrostatic latent image forming potential V1 is charged. Charge the charged force F to E (see figure (
1)).

Depending on the kneading, the timing of the start of light refraction by the luminous flux 4 on the detection area is adjusted as shown in Fig. 4 (I +7) to obtain a charging pattern as shown in Fig. 4 (Ill). In addition, in the electrostatic latent image forming area, an electrostatic latent image is formed by exposure Kj by the J light beam. This is expressed by a broken line in Diagram 4 (1n) for 1 year old.

In the method shown in Fig. 5, after the charger 2 charges the photoreceptor 1 with voltage Vp, V+02 steps ((+) in the same figure), the light emission of the erase lamp 3 is applied to the detection area having the voltage Vp. Timing t a-5 diagram (I[
), and by determining the timing of the start of the green light by the light beam at the tip of the stick as shown in the same figure (m), the bottle-Figure 5 (I
A charging pattern as shown in V) is obtained.

In the method shown in Figure 6, the photoreceptor l is charged +
-2VC, the voltage Vp is charged to V+02 stages (simultaneously (I)). The timing of the start of exposure is determined by the voltage Vp.
As shown in (1) in the same figure, for a detection area with a
The carp light flux is blocked (the part indicated by reference numeral 6-1). kof''
1. [Thus, a charged putter 7 as shown in Figure 6 (II) is obtained.

In the above three examples, the charging pattern is formed outside the leading end of the electrostatic latent image forming area, but it may also be formed outside the rear end of the upper area. Further, the present invention can be applied to a case where the charging potential of the charging pattern is smaller in absolute value than the potential for forming an electrostatic latent image, and the charging polarity can also be applied to a square corner.

Although the electrophotographic recording method has been described above, it goes without saying that the present invention can also be applied to an electrostatic recording method using a dielectric latent image carrier. In such a case, in order to form a step difference between the charging potential of the charging pattern and the electrostatic latent image forming potential, for example, the signal voltage applied to the multi-needle electrode should be applied in two stages, one for the charging pattern and the other for forming the latent image. You should switch to

[Brief explanation of the drawing]

Figure 1 is an explanatory front view schematically showing only the essential parts of an example of an electrophotographic apparatus to which the present invention is applied; Figures 2 and 3 are diagrams showing the detection area, charging pattern 7, and pattern image. A diagram for explaining concentration detection, FIG. 4 is a diagram for explaining one method of forming a charging pattern, FIG. 5 is a diagram for explaining another method for forming a charging pattern, and FIG. FIG. 7 is a diagram for explaining another method of forming a charging pattern. ] . . . Photoreceptor as a light guide type open latent image carrier, 2 . . . Charger, 3 . . Erase lamp, 4 . . . Exposure light flux. 5... Clear image device, 7... Transfer charger, 6...
・Detection system, 8...Cleaning device, DJ...Detection area, D2...Electrostatic latent image forming area

Claims (1)

[Claims] A detection area is set outside the electrostatic latent image forming area of the latent image carrier, and during recording, a predetermined charging pattern image is formed in the detection area, and this charging pattern is developed. , obtain a pattern image using toner, f) detect the density of the pattern image, and control the quality of an electrostatically recorded image based on the detection result, which method includes charging the charging pattern 7 formed in the detection area Image quality control in the electrostatic Ge recording method, characterized in that the potential is set one step lower in absolute value than the electrostatic latent image forming potential, making it easy to remove the pattern image formed in the detection area. Method.