JPS59128563A - Latent image carrier surface condition detector - Google Patents

Abstract

PURPOSE:To monitor surface condition of latent image carrier at all times and obtain a good copy by providing a device that compares an output signal from a light detecting array with a reference signal that indicates good surface condition of latent image carrier. CONSTITUTION:A light detecting array 10 consisting of plural light detecting elements P1-Pn, opposite to the surface of a photosensitive body drum 1 in the direction that crosses direction of movement and a long fluorescent lamp 11 placed parallel to the array are provided. Light irradiated from the fluorescent lamp 11 is reflected by the surface of the drum 1 and received by each light detecting element Pi and outputted after photoelectric conversion. The output signal from the light detecting element Pi is inputted to a multiplexer 12 and converted to digital signal by an A/D convertor 13, and compared with a reference signal that indicates good surface condition of the drum in a controlling circuit 14. In this case, a microcomputer is utilized. The reference value is stored in an ROM and compared with the detected signal in a CPU.

Description

TECHNICAL FIELD The present invention relates to a device for detecting the surface condition of a latent image bearing member such as a photoreceptor or a transparent conductor in an electrophotographic device or an electrostatic recording device.

(Prior Art) A latent image carrier is an extremely important element that influences image quality because an image is formed on its surface.

For example, if the surface is scratched, white streaks or black streaks will appear in the copied image. Conventionally, the surface condition of the latent image carrier can only be known later by looking at the copy.

(Object of the Invention) An object of the present invention is to provide a surface condition detection device that constantly monitors the surface condition of a latent urine carrier and obtains good copies.

The detection device according to the present invention includes a large number of photosensors arranged in a direction transverse to the direction of movement of the latent image carrier, facing the surface of the latent image carrier in order to optically detect the surface state of the latent image carrier;
and means for comparing the output signal from the photo sensor with a reference signal representative of a good latent image carrier surface condition.

Hereinafter, one embodiment of the present invention will be described with reference to all the accompanying drawings.

(Structure of the Invention) FIG. 1 schematically shows an example of an electrophotographic apparatus to which the present invention is applied. A charging churn #2, an exposure optical system 3, and a developing device 4 are arranged around the photoreceptor drum l, which has a conductive insulating layer on its surface, along the clockwise rotation direction.
, a transfer charger 5, a separation charge cello, a cleaning device 7, a static elimination lamp 8, and the like are arranged. When the surface of the photosensitive drum 1 is uniformly charged to a predetermined polarity by the charging charger 2, a light image of the original to be copied is irradiated thereon through the exposure optical system 3. As a result, the charges on the surface of the photoreceptor drum 1 are selectively dissipated, and an electrostatic latent image corresponding to the original image is formed thereon.

This electrostatic latent image is developed by supplying toner charged with the opposite polarity from the developing device 4.

A transfer paper 9 sent in synchronization with this image formation is superimposed on this developed toner image, and the toner image is transferred by being charged by the transfer charger 5 with a size and polarity that attracts the toner image. It is transferred onto paper 9. Subsequently, the transfer paper 9 is separated from the surface of the photoreceptor drum 1 after being neutralized by the separation charger 6, enters a fixing device, receives the fixation of the toner image, and is discharged to a copy tray. The surface of one photoreceptor drum 1 has residual toner removed by a cleaning device 7 and residual potential removed by a static elimination lamp 8 .

As shown in Fig. 2, the detection device according to the present invention includes a photosensor array 1o consisting of a large number of photosensors 21 to 2 arranged opposite to the surface of the photoreceptor drum 1 in a direction transverse to the direction of movement of the photoreceptor drum 1. The light source 11 includes a light source 11 having a flat emission distribution, such as a long fluorescent lamp arranged in two parallel directions. This light source 11 may be a light emitting diode integrated into each photosensor P. The light emitted from the light source 11 is reflected on the surface of the photosensitive drum 1, and the reflected light is received by the valley photosensor P, photoelectrically converted, and output. The output signals from each photosensor P are input to the multiplexer 12 as shown in FIG. 3, and then sequentially converted into dental signals by the A/D converter 13.
The control circuit 14 compares the signal with a reference signal representing a good surface condition of the photoreceptor drum.

For example, if an area 1a is formed on the surface of the photoreceptor drum 1 from which residual toner has not been sufficiently removed, as shown in FIG. Sensor P3
The output of ~P5 is lower than the output when the surface condition is good as shown in FIG. Therefore, when the output decreases below an allowable reference value, the apparatus is stopped and maintenance is performed.

Comparison with the reference value is performed in the control circuit 14,
This control circuit 14 utilizes a microcomputer built into the copying machine. The reference value is stored in the ROM and compared with the detection signal in the CPU. The output of the comparison result is used to display a warning, but it may also be input to the drive circuit 15 to cause the copying machine itself to perform an operation to restore the surface condition of the photoreceptor to normal. For example, if the cleaning device 7 is a fur brush type, the number of rotations of the fur brush may be increased, the amount of penetration into the photoconductor may be increased υ, and if the cleaning device is a blade cleaning device, the blade pressure on the photoconductor may be increased or the contact angle may be increased. By increasing the amount of penetration, the dirt area 1a is removed.

Further, by disposing the photosensor array 10 and the light source 11 between the developing device 4 and the transfer charger 6, forming a belt-shaped latent image pattern parallel to these, and developing this, the developed density can be detected. By comparing this with the base thread density signal, uneven charging, uneven illuminance, uneven development, etc. can be detected. Furthermore, by placing these between the separation charger 6 and cleaning device #7 and detecting the surface condition of the photoreceptor after the development pattern has been transferred, the amount of residual toner attached can be detected, and this can be used as a reference value. By comparison, it is possible to detect uneven transfer.

In this case, since the transfer efficiency can also be detected, if the efficiency decreases, the detection result is fed back to the total transfer charger 5 to increase the transfer current. Further, since the amount of residual toner can be known, this can be fed back to the cleaning device 7, and specifications such as the above-mentioned fur brush rotation speed can be appropriately determined to optimize the cleaning conditions.

(Effects of the Invention) As described above, according to the detection device of the present invention, it is possible to precisely detect the surface condition of a latent image carrier such as a photoreceptor. This makes it possible to quickly identify the causes of copy defects and take countermeasures. Furthermore, if the detection results are automatically fed back to each device unit, copies can always be made with a good surface condition of the latent image carrier.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an electrophotographic apparatus to which the present invention is applied, FIG. 2 is a diagram showing the arrangement of a photosensor array and a light source in an embodiment of the present invention, and FIG. , a block diagram of an electric circuit in an embodiment of the present invention, and FIG. 4 is a graph showing detection results in an embodiment of the present invention. 1... Photosensitive drum, 10... Photo sensor array, 11... Light source.

Claims (1)

[Claims] A photosensor array consisting of a large number of photosensors arranged in a direction transverse to the moving direction of the latent image carrier facing the surface of the latent image carrier to irradiate the surface of the moving latent image carrier with a source and receive the reflected light; , means for comparing the output signals from each of the photosensors with a reference signal representing a good surface condition of the latent image carrier.