JPS6024565A - Color toner concentration detector - Google Patents

Abstract

PURPOSE:To eliminate the effect on a photodetector of reflected light due to a color toner in a detector composed of a conductive probe facing a conductive mask and a light emitting element and a photodetector both located across the mask, by equalizing the incident angle of light emitted from said element on said probe to its angle of light reflected on the probe, and regulating its angle to or above a specified value. CONSTITUTION:Light emitted from a light emitting element 9a passes through a conductive mask 11 and it is reflected on the surface of a conductive probe 8 at a reflection angle (r). Light again passes through the mask 11 and reaches a photodetector 9b. The probe 8, the element 9a, and the photodetector 9b are arranged so as to equalize the incident angle (i) to the reflection angle (r). Since the light emitted from the element 9a is incident on the mask 11 at an incident angle of >=60 deg., the photodetector 9b never receive the light reflected with a color toner on the mask 11, even if the light emitted from the element 9a is reflected in the direction of the arrow alpha.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a color toner density detection device for a color electronic copying machine. This invention relates to a device that can automatically detect.

Prior art Toner e of a developer made of black toner in a conventional electronic copying machine
As a method for detecting the degree of infrared radiation, a method is known in which detection is performed based on a change in the amount of infrared light transmitted from the developer based on the development characteristics of the developer.

However, when a similar method is adopted to detect the density of color toner in a color electronic copying machine, it is difficult to detect the density of color toner with high accuracy because the spectral reflectance of color toner is high in the infrared region. This will be explained more specifically. FIG. 1 is a diagram showing an overview of magnetic brush development, FIG. 2 is a diagram showing an overview of a toner concentration detection device, and FIG. 3 is a diagram showing details of a conductive mask of the toner concentration detection device. .

In FIG. 1, reference numeral 1 denotes a photosensitive drum, which rotates in the clockwise direction of the arrow as shown. 2 is a developing device installed opposite to the photosensitive drum 1; 3 is a developing roll;
Reference numeral 4 at the rear is a developer conveyance roll. Further, above the developing roll 3, there is a spike regulating plate 5 for regulating the height of the magnetic sill V3α, and a developer plate for transporting the developer peeled off from the developing roll 3 into the developer housing 2a by the spike regulating plate. A conveying plate 6 and a developer scraping plate 7 for scraping off the developed developer also from the developing roll 3 are installed.

Further, a roll-shaped conductive probe 8 is provided above the developing roll 3.
is installed, and a toner concentration detector 9 as shown in FIG. 2 is installed near the conductive probe 8. A permanent magnet 10 is embedded in a part of the outer circumference of the conductive probe 8, and the concentration detector 9 includes a light emitting element 9a that emits light toward the surface of the conductive probe 8, and a light emitting element 9a that emits light toward the surface of the conductive probe 8. It is composed of a light receiving element 9b that receives reflected light from the light receiving element 9b and a conductive mask 11. As shown in FIG. 3, the conductive mask 11 is composed of a transparent glass 12 coated with a conductive member 13. Light emitted from the light emitting element 9α in the direction of the arrow (dashed line) in FIG. 2 passes through the conductive mask 11, is reflected by the surface of the conductive probe 8, passes through the mask 11 again, and reaches the light receiving element 9h. do. Since color toner is attached to the conductive mask 11, the light is weakened while passing through the mask twice, and the scene that enters the light receiving element 9bK is the amount of toner attached to the mask IC, that is, the toner concentration. The larger it is, the less it will be. Since the light receiving element converts the amount of light received into an electrical signal, a certain relationship can be obtained between this electrical signal and the toner concentration.
Therefore, the toner concentration can be determined from the electric signal of the light receiving element. However, since the cyan, magenta, or yellow color toner adhering to the ILL12 mask 11 all exhibit high spectral reflectance in the infrared region, the light emitted from the light emitting element 9α is caused by the color toner on the mask 11 in the direction of the arrow ( Solid line) K is reflected, and part of it enters the light receiving element 9b as disturbance light, affecting the amount of light received and making it difficult to accurately measure the density of color 1 toner.

OBJECTS OF THE INVENTION Accordingly, the objects of the present invention are influenced by the spectral reflection properties of color toners. It is an object of the present invention to provide a color toner density detection device that can detect the density of color toner with high reliability without causing problems.

Structure of the Invention According to the present invention, the above object is to detect conduction of light from the light emitting element in a developer concentration detection device consisting of a conductive probe, a light emitting element, and a light receiving element which are provided facing each other through a conductive mask. The angle of incidence i and the angle of reflection r on the sex probe
This is achieved by making the angles equal to each other and making the head length 60' or more.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

As shown in FIG. 1, when the photosensitive drum 1 on which the electrostatic latent image is formed rotates clockwise and the developing roll 3 rotates counterclockwise, a magnetic brush 3α is formed. The height of the magnetic brush 3α is regulated by a bristling regulating plate 5, and the magnetic brush 3α comes into contact with the photosensitive drum 1 to develop an electrostatic latent image. The developer that has completed development is scraped off from the developing roll by the developer scraping plate 7, collected into the developing device 2, sufficiently stirred, and then conveyed to the developing roll 3 by the conveying roll 4.
The hunting brush 3α is formed again. At this time, the panicle regulating plate 5
The developer separated by the magnetic brush 3α is collected into the developing device 2 by the developer transport plate 6.

On the other hand, the magnetic brush 3a is in contact with a conductive probe 8 installed above the developing roll 3, and the developer on the magnetic brush 3α is attracted to a permanent magnet lO embedded in the conductive probe 8, where a new magnetic Forming the brush 8α (Fig. 2)
. This magnetic brush rotates clockwise together with the conductive probe 8 and comes into contact with the conductive mask 11 of the concentration detector in the vicinity of the conductive probe. At this time, an AC square wave is applied to the conductive member 13 constituting the conductive mask 11, and when a voltage of the same polarity as the developer is applied, the conductive mask 11 is in a clean state. At the moment when a voltage with a polarity different from that of the color toner is applied, the color toner and the carrier that were electrostatically adsorbed to each other are separated, and the color toner is adsorbed only to the surface of the conductive member 13 (Fig. 3). . At this time, the light emitted by the light emitting element 9α constituting the concentration detector 9 passes through the transparent glass 12, is reflected by the conductive probe 8, and passes through the transparent glass 12 again to the light receiving element 9h.
incident on . At this time, the amount of incident light that enters the light receiving element 9b corresponds to the amount of color toner adsorbed onto the conductive member 13, that is, the density of the color toner, so that the density of the color toner can be extracted as an electrical signal. ing.

According to the color toner density detection device of the present invention.

As shown in FIG. 4, the light emitted from the light emitting element 9α passes through the conductive mask 11, is reflected by the surface of the conductive probe 80 at a reflection angle r, passes through the conductive mask 11 again, and reaches the light receiving element. It is supposed to reach. The conductive probe, the light emitting element, and the light receiving element are arranged so that the angle of incidence i and the angle of reflection r are equal. According to the present invention, the light emitted from the light emitting element 9α is 600 nm to the conductive mask 11.
Since the light is incident at an incident angle of .degree. or more, even if the light from the light emitting element side is reflected in the direction of the arrow α (dotted line) by the color toner on the conductive mask, it will not be received by the light receiving element. From No. 1, according to the apparatus of the present invention, the above arrow α
Since the reflected light in the direction does not directly enter the light receiving element, the color toner density can be detected with very high accuracy. Furthermore, if the amount of color toner replenishment is controlled based on the 0 degree detection signal indicated by the light receiving element, copies with a stable density can always be obtained.

Effects of the Invention According to the present invention, the influence of the reflected light by the color toner on the conductive mask on the optical element is eliminated, and there is no disturbance caused by the reflected light when detecting the color toner concentration, so the color can be detected with high accuracy. Toner concentration can be detected.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a developing device of an electrophotographic copying machine, FIG. 2 is a diagram showing a developer concentration detection device, FIG. 3 is an enlarged view of a conductive mask, and FIG. 4 is a diagram for explaining the present invention. It is a diagram. Symbols in the figure: 1...Photosensitive drum 1, 2...Developing device, 3.-
・Developing roll, 4... Conveyance roll, 5... Ear standing regulation plate, 6... Developer conveyance plate, 7... Developer scraping plate, 8... Conductive Pro'zo, 9 ... Current agent 0
degree detector, 10... permanent magnet, 11... conductive mask, 12... transparent glass, 13... electrically conductive member. (3 others)

Claims (1)

[Claims] In a developer concentration detection device consisting of a conductive probe, a light-emitting element, and a light-receiving element, which are provided facing each other through a conductive mask, the angle of incidence and reflection of light from the light-emitting element on the conductive probe are made equal. A color toner concentration detection device characterized in that the angle of incidence is 60' or more.