JPH052302A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] An image formation in which the toner density detection means for detecting the toner density of a patch does not become dirty and the toner density can always be detected stably, and the toner density is controlled correctly. To provide a device. A toner density detecting means for detecting the toner density of a patch formed on an image carrier is arranged inside the transfer means, and has a cleaning means for the transfer means. [Effect] The sensor surface of the toner concentration detecting means is not contaminated, stable toner concentration detection is possible, and correct toner concentration control is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for stabilizing the density of a toner image developed on an image carrier.

[0002]

2. Description of the Related Art Conventionally, as a recording system for forming a full-color image, an electrophotographic system, an ink jet recording system, a thermal transfer recording system and the like are known.

Among them, the electrophotographic system is capable of high speed and can be used for plain paper, and in recent years, product development has been further advanced.

In forming a full-color image of the electrophotographic system, many developing devices use a two-component developer having a toner and a carrier from the viewpoint of the tint of the image. In this case, the developing device is used for image formation. When the toner in the toner is consumed, it is necessary to replenish the developing device with toner commensurate with the consumption. Therefore, the toner concentration is detected to control the toner concentration, that is, the developer concentration detecting device and the control device (hereinafter, The toner density is kept constant by ATR).

FIG. 2 shows an example of a conventional image forming apparatus of this type. In FIG. 2, 1 is a bidirectional light emitting LE
D, 2 are photodiodes, 3 is a developing sleeve, and 4 is an image carrier.

That is, the inside of the developing device 9 arranged facing the image carrier 4 is divided into a developing chamber 11 and a stirring chamber 12 by a partition wall 10 extending in the direction perpendicular to the plane of FIG. The upper portion of the partition wall 10 is open, and the excess developer in the developing chamber 11 is collected by the screw portion on the stirring chamber side and circulated. The developing chamber 11 and the stirring chamber 12 store a two-component developer having toner and carrier, and the photodiode 2 reflects the reflection from the patch 20 to which the replenishment toner is irradiated by the LED 1 from the upstream side of the stirring chamber screw conveyance. Then, the toner is converted into a signal value by this, and the toner corresponding to the difference from the reference value is replenished.

The developing chamber 11 of the developing container of the developing device 9 has an opening at a position corresponding to the developing area facing the image carrier 4, and the developing sleeve 3 is partially exposed at the opening 14. It is rotatably installed.

The developing sleeve 3 is made of a non-magnetic material,
During the developing operation, it rotates in the direction of the arrow shown in the drawing, and the magnet 13 serving as a magnetic field generating means is fixed inside thereof.

When the developing sleeve 3 is developed for visualizing the latent image on the image carrier 4, AC and DC biases are applied by the power source 15 and the toner adheres from the developing sleeve 3 to the image carrier 4. .

The toner image on the image carrier 4 is transferred onto the transfer drum 16
The toner image transferred onto the recording material, which is not shown in the drawing, is transferred to the recording material due to the generation of an electric potential by the transfer charger 17 on the recording material (not shown), and is cleaned by the cleaning unit 18.

As described above, the patch 20 which is the reference density pattern is formed on the image carrier 4 and developed under a certain condition, and the reflection density of this toner image is detected by the photodiode 2 to control the toner density. It is configured to perform a patch inspection.

[0012]

However, in the conventional example shown in FIG. 2, L is provided near the image carrier 4 and the developing device 9.
Since the patch detection sensor including the ED1 and the photodiode 2 is arranged, there is a problem that the sensor surface is soiled due to toner scattering and the like, and the toner concentration control is not performed properly.

The present invention is intended to solve the above problems. That is, an object of the present invention is to provide an image forming apparatus in which a sensor surface such as a patch detection sensor is not contaminated and stable toner density detection is always possible, and correct toner density control is performed. It is a thing.

[0014]

In order to achieve the above object, the image forming apparatus of the present invention is a toner for detecting the toner density of a patch developed with a latent image formed on an image carrier of an electrophotographic recording device. The density detecting means is arranged inside the transfer means, which is the opposite side of the image carrier with respect to the surface of the transfer means,
In addition, a cleaning means for cleaning the surface of the transfer means is provided.

[0015]

According to the present invention, since the toner density detecting means for detecting the toner density of the patch is arranged inside the transfer means, the sensor surface of the detecting means is not contaminated by scattered toner and the like. Since the surface of the transfer unit is cleaned by the cleaning unit, it is possible to always detect the toner density in a stable manner.

[0016]

FIG. 1 shows a first embodiment of the present invention. In FIG. 1, 3 and 4, 9 to 18 are the same as the members described in FIG.

Reference numeral 21 denotes a bidirectional light emitting type LED, 2
Reference numeral 2 denotes a photodiode, which is provided inside the transfer drum 16. The transfer drum 16 is made of polyvinylidene fluoride having a thickness of 1 mm, which is almost transparent. It should be noted that the partition wall 10 is formed with an opening for communicating the developing chamber 11 with the stirring chamber 12 at the front and rear ends in FIG. Reference numeral 19 is a cleaning means for cleaning the surface of the transfer drum 16.

FIG. 3 is a flow chart of the first embodiment of the present invention. Explaining with reference to FIG. 3, first, in step S101, a latent image of the patch 20 for reading the toner density is formed on the image carrier 4, and in step S102 development is performed. In step S103, the patch 20 is used as the image carrier 4
A photodiode 22 that detects the irradiation light of an LED 21 for toner concentration detection arranged at a position through the transfer drum 16 immediately before coming into contact with the transfer drum 16 that has started to rotate with
The toner density is controlled by the signal.

At this time, the transmittance of the LED light having a peak at 950 nm of the transfer drum 16 was about 80%, and there was no influence due to light scattering or the like.

Then, in step S104, the transfer drum 16 is cleaned by roller or blade cleaning means 19
Always cleans.

As described above, the toner density detecting means (LED 21, photodiode 22) is provided inside the transparent or nearly transparent transfer means (transfer drum 16), and the transfer means is constantly cleaned, so that the detection surface becomes dirty. It is possible to control the toner density stably without depending on

As the transfer means, any means such as a belt-like means may be used as long as the object can be achieved.
The relation between the transparency of 21 and the transfer means may be any relation between the irradiation light source and the transfer means as long as the irradiation light can pass through the transfer means to some extent. Next, some embodiments of the present invention will be described.

(Second Embodiment) In the above-mentioned first embodiment, an example of toner density control using only the patch reading sensor arranged inside the transfer means has been described, but in the present embodiment, it is combined with the video count ATR. In the continuous copy sequence, the output levels of the digital image signals are integrated for each pixel, and this is converted into a replenishment amount as a video count number to replenish toner. Before and after that, the video count supply is corrected by using the patch detection according to the present invention.

(Third Embodiment) In this embodiment, the patch detection sensor inside the transfer means according to the present invention is also used as a sensor when a recording material such as paper or OHP sheet is jammed.

The algorithm will be described with reference to FIG.

First, a normal image or a latent image of a patch is created in step S101, developed in step S102, and then it is determined in step S103 whether it is a patch or a normal image. If it is a patch, the patch sensor is used in step S104. The photodiode 22 detects the reflected light of the LED 21, the toner density is controlled, and the transfer drum 16 is cleaned in step S105. If the image is a normal image in step S103, the patch sensor is used as a jam sensor, and in step S106, the light reflected by the LED 21 is reflected after a time from when the front end of the recording material crosses the irradiation light of the LED 21 to when the rear end passes normally. If the light is sufficiently detected by the photodiode 22, the light is left as it is, and if the reflected light of the LED 21 cannot be detected after a predetermined time, it is determined that a jam has occurred before the transfer, and a jam display is performed in step S109 to notify the user. Is.

[0027]

As described above, according to the present invention,
Since the toner density detecting means for detecting the toner density of the patch is arranged inside the transfer means, the sensor surface of the detecting means is not contaminated by the scattered toner and the surface of the transfer means is cleaned by the cleaning means. As a result, stable toner density detection is always possible, and correct toner density control is performed.

[Brief description of drawings]

FIG. 1 is a side view showing a first embodiment of the present invention.

FIG. 2 is a side view showing an example of a conventional technique.

FIG. 3 is an explanatory diagram of an operation of the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of an operation of the third embodiment of the present invention.

[Explanation of symbols]

3 ... Developing sleeve 4 ... Image carrier 9 ... Developing device 16 ... Transfer drum 19 ... Cleaning means 20 ... Patch 21 ... LED 22 ... Photo diode

Claims (3)

[Claims] 1. A toner density detecting means for detecting the toner density of a patch developed with a latent image formed on an image carrier of an electrophotographic recording apparatus is on the opposite side of the surface of the transfer means from the image carrier. An image forming apparatus comprising: a cleaning unit that is disposed inside the transfer unit and that cleans a surface of the transfer unit. 2. The correction means of the toner density control device for supplying toner according to the reading result of the image reading means, wherein the correction is made by the output result of the toner density detecting means at a predetermined timing. Image forming apparatus. 3. The image forming apparatus according to claim 1, wherein the toner density detecting means is also used as a jam detecting means.