JPS63133166A - Photosensitive unit with life expiration detecting function - Google Patents

Abstract

PURPOSE:To detect the expiration of life of a photosensitive body with a simple constitution by detecting the surface potential of an exposed part, which is exposed with a prescribed quantity of light, and that of a non-exposed part after electrifying the photosensitive body and displaying the expiration of life when the difference between detected surface potentials is smaller than a preliminarily set value. CONSTITUTION:The surface potential of the non-exposed part just before an image area of the photosensitive body uniformly electrified by an electrifying charger 2 and the surface potential of a texture part, which corresponds to the leading part having no characters, patterns, or the like of an original, in the image area are detected by a surface potential sensor 4, and results are inputted to a CPU 8, and the difference of surface potential between the non- exposed part and the exposed part (texture part) is compared with the preliminarily set value; and if the former is smaller than the latter, information indicating that the life of the photosensitive body expires is displayed on a display device 9 on an operation panel of a copying machine body. Thus, the photosensitive body is always used up to expiration of its life to avoid waste.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a photoreceptor unit with a life detection function for an electrostatic recording device.

Prior Art In electrostatic recording devices that utilize an electrostatic photographic process, such as electrophotographic copying machines, laser printers, and facsimile machines, a drum-shaped or endless belt-shaped photoreceptor is uniformly charged, and then image exposure is performed to record images on the photoreceptor. An electrostatic latent image is formed on the toner image, this is visualized as a toner image by a developing means, and is transferred to a transfer paper under the action of a transfer charger and fixed to complete the recording.

By the way, the performance of photoreceptors used in electrostatic recording devices deteriorates with repeated use, and even if exposed to a moderate amount of light after being charged, the static electricity is not removed sufficiently and the potential does not drop, resulting in a difference between the image area and the non-image area. The potential difference with the image area decreases, and the contrast deteriorates.

Conventionally, the lifespan of a photoconductor was estimated indirectly by counting the number of times the photoconductor was used or the number of sheets passed through a recording device using a counter, and It was normal to have the unit replaced.

According to this method, the number of sheets that are considered to have reached the end of their lifespan is set, taking into account margins due to variations in the characteristics of the photoconductor itself, so the photoconductor unit is replaced even though it actually still has its lifespan. This resulted in a lot of waste.

Purpose The present invention has been made in view of the above-mentioned circumstances of the conventional method for estimating the lifespan of a photoreceptor in an electrostatic recording device, and an object of the present invention is to provide a photoreceptor unit that can detect the lifespan of a photoreceptor with a simple configuration. do.

Structure In order to achieve the above-mentioned object, the photoreceptor unit of the present invention is provided with a photoreceptor surface potential detection means along the photoreceptor surface between the image exposure position and the development position of the photoreceptor, and the photoreceptor surface potential detection means is provided to determine the charged location of the photoreceptor. The present invention is characterized in that it is provided with means for detecting the surface potential between the exposed area and the non-exposed area exposed to the light amount, and displaying that the life span has been reached when the difference therebetween becomes less than or equal to a preset value.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram schematically showing the structure around a photoreceptor of an electrostatic recording apparatus to which the present invention is applied.

A charging charger 2, an exposure position 3, a surface potential sensor 4 according to the present invention, a developing unit 5, a transfer charger 6, and a static elimination lamp 7 are arranged around the photosensitive drum 1 in the order of rotation direction indicated by an arrow. Since the image forming process using process equipment other than the surface potential sensor 4 is well known, a description thereof will be omitted.

Now, as shown in Figure 2, the surface potential of the photoreceptor remains high in the non-exposed area, with the potential charged by the charger remaining almost unchanged (lowering by the amount of dark decay); In the background portion of the exposed original or the exposed portion that is exposed to light from the blinking laser beam of the laser printer, the potential caused by the charger on the photoreceptor is removed by light, and a small amount of potential remains as a residual potential. The residual potential varies depending on the density of the background, and in the case of paintings, various levels of residual potential occur depending on the density in halftone parts.

By the way, in general, as a photoreceptor is used repeatedly, the residual potential of the exposed portion gradually increases from the state shown by the broken line in Figure 2 to the state shown by the solid line even when exposed with the same amount of light, and the negative-positive process In this case, toner does not adhere to the photoreceptor, and in the case of a positive-positive process, background stains occur and image quality deteriorates. In other words, the life of the photoreceptor has come to an end.

Therefore, the surface potential sensor 4 detects the surface potential of the non-exposed part of the photoreceptor immediately before the image area, which is uniformly charged by the charger 2, and the background part of the image area where there is no first character, painting, etc. of the document. The result is input to the CPU 8, and the difference in surface potential between the non-exposed area and the exposed area (background area) is compared with a preset value, and if the difference is less than the set value, the copying machine, etc. A display 9 on the operation panel of the main body indicates that the life of the photoreceptor has come to an end. Even if this message appears, the photoconductor does not immediately become unusable, so it can be used until you call a service person or purchase the photoconductor unit, reducing machine downtime. I can do it.

Note that the exposure unit that measures the surface potential may expose a pattern of a predetermined density without using the background portion of the document.

Effects As described above, according to the present invention, the lifespan of a photoreceptor can be directly measured, so that the photoreceptor can always be used to its fullest life and waste can be avoided.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing the structure around a photoreceptor of an electrostatic recording apparatus to which the present invention is applied, and FIG. 2 is a graph showing the difference in surface potential between an exposed area and a non-exposed area. 1... Photoreceptor 2... Charger 3.
...Exposure section 4...Surface potential sensor 5...
Developing device 8...CPU9...Display unit

Claims (1)

[Claims] A photoreceptor surface potential detection means is provided along the surface of the photoreceptor between the image exposure position and the development position of the photoreceptor of the electrostatic recording device,
After the photoconductor is charged, a means is provided to detect the surface potential between the exposed area and the non-exposed area exposed to a predetermined amount of light, and to indicate that the life span has been reached when the difference between them becomes less than a preset value. Characteristic photoconductor unit.