JPH0544673B2 - - Google Patents

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 As a conventional method for detecting the toner concentration of a developer made of black toner in an electronic copying machine, a method is known in which the development characteristics of the developer are detected by changes in the amount of infrared light transmitted from 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 the color toner with high accuracy because the spectral reflectance of the 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;
is a developing roll, and 4 behind it is a developer conveying roll. Further, above the developing roll 3, there is a spike regulating plate 5 for regulating the height of the magnetic brush 3a, and a developer 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 developed developer from the developing roll 3 are installed. Further, a roll-shaped conductive probe 8 is arranged above the developing roll 3.
A toner concentration detector 9 as shown in FIG. 2 is installed near the toner concentration detector 9 . 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 light 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 9a 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 9b. do. Conductive mask 1
Since the color toner is attached to the mask 11, the light is weakened while passing through the mask twice, and the amount of light incident on the light receiving element 9b increases as the amount of toner attached to the mask 11, that is, the toner concentration increases. It becomes less. Since the light receiving element converts the amount of light received into an electrical signal, a certain relationship is obtained between this electrical signal and the toner concentration, and the toner density can be determined from the electronic signal of the light receiving element. However, since the cyan, magenta, or yellow color toner adhering to the mask 11 all exhibit high spectral reflectance in the infrared region, the light emitted from the light emitting element 9a is reflected by the color toner on the mask 11 in the direction of arrow α ( A part of the reflected light 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 toner.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide a color toner density detection device that can detect the density of color toners with high reliability without being affected by the spectral reflection characteristics of color toners.

Structure of the Invention According to the present invention, the above object includes a conductive probe, and a light emitting element and a light receiving element provided opposite to the conductive probe through a conductive mask, and the light from the light emitting element is transmitted to the conductive probe. In the color toner detection device, the color toner detection device reflects light by the conductive probe through the conductive mask, and receives the reflected light by the light receiving element,
Among the light incident on the conductive mask from the light emitting element at an incident angle i ₁ , the light reflected from the conductive mask at a reflection angle i ₁ is prevented from entering the light receiving element. A color toner concentration detection device characterized in that the light emitting element and the light receiving element are arranged such that an incident angle at which light enters the conductive mask is _i2 , and _i1 and _i2 are different. Ru.

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

As shown in FIG. 1, the photosensitive drum 1 on which the electrostatic latent image is formed rotates clockwise, and the developing roll 3
When rotated counterclockwise, a magnetic brush 3a is formed. The height of the magnetic brush 3a is regulated by a bristling regulating plate 5, and the magnetic brush 3a 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 magnetic brush 3a is formed again. At this time, the developer peeled off from the magnetic brush 3a by the spike control plate 5 is transferred to the developing device 2 by the developer transport plate 6.
will be collected within.

On the other hand, the magnetic brush 3a is in contact with the conductive probe 8 installed above the developing roll 3.
The developer on the surface a is attracted to the permanent magnet 10 embedded in the conductive probe 8, and forms a new magnetic brush 8a there (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 of a polarity different from that of the color toner is applied, the color toner and the carrier that have been electrostatically attracted to each other are separated, and the color toner is attracted only to the surface of the conductive member 13 (FIG. 3). On this occasion,
Light emitted from the light emitting element 9a constituting the concentration detector 9 passes through the transparent glass 12, is reflected by the conductive probe 8, passes through the transparent glass 12 again, and enters the light receiving element 9b. At this time, the light receiving element 9b
Since the amount of incident light incident on the conductive member 13 corresponds to the amount of color toner adsorbed on the conductive member 13, that is, the color toner density, the color toner density can be extracted as an electrical signal.

According to the color toner concentration detection device of the present invention,
As shown in FIG. 4, the light emitted from the light emitting element 9a passes through the conductive mask 11 at an incident angle of i ₁ and is reflected on the conductive probe 8, and then is reflected at an incident angle of i ₂
The light receiving element 9b passes through the conductive mask 11 again.
It is starting to reach . The angles of incidence i ₁ and i ₂ are given different values to prevent some of the detection light reflected by the conductive mask before reaching the conductive probe from directly entering the photodetector. The reflected light α with a reflection angle i ₁ emitted from the light emitting element and reflected by the color toner on the conductive mask, that is, the specularly reflected light, is not received by the light receiving element. Here, the difference between i ₁ and i ₂ may be 10° or more, and i ₁ is preferably 60° or more. According to the apparatus of the present invention, the color toner density can always be detected with high accuracy because it is not affected by the reflected light α. Furthermore, by controlling the amount of color toner replenishment based on the density detection signal indicated by the light receiving element, copies with stable density can always be obtained.

Effects of the Invention According to the present invention, the influence of the spectral reflection light caused by the color toner on the conductive mask on the light-receiving element is eliminated, and the influence of the emission spectrum of the light-emitting element can also be ignored. Concentration detection can be performed.

[Brief explanation of the drawing]

Figure 1 shows the developing device of an electronic copying machine, Figure 2 shows the developing device of an electronic copying machine.
The figure shows 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. Codes in the figure: 1...Photosensitive drum, 2...Developing device, 3...Developing roll, 4...Transport roll, 5...
... Ear standing regulation plate, 6 ... Developer transport plate, 7 ... Developer scraping plate, 8 ... Conductive probe, 9 ... Developer concentration detector, 10 ... Permanent magnet, 11 ... Conductive Mask, 12... Transparent glass, 13... Conductive member.

Claims (1)

[Claims] 1 It has a conductive probe and a light emitting element and a light receiving element provided opposite to it through a conductive mask, the light from the light emitting element is reflected by the conductive probe through the conductive mask, and the In a color toner detection device in which reflected light is received by the light receiving element, the light that is incident on the conductive mask from the light emitting element at an incident angle of i ₁ is reflected by the conductive mask at a reflection angle of i ₁ . The incident angle at which the reflected light from the conductive probe is incident on the conductive mask is adjusted so that the light does not enter the light receiving element.
i ₂ , and the light emitting element and the light receiving element are arranged so that i ₁ and i ₂ are different.