JPH0442674B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a color toner density detection device for a copying machine that detects the density of color toner based on the amount of reflected infrared light irradiated onto the color toner.

(Prior Art) Examples of conventional color toner density detection devices for copying machines include the following.

(1) For example, place a light emitting element that emits infrared light and a light receiving element that receives it on the opposite side of the transparent glass, develop the transparent glass with color toner, and detect the amount of infrared light that passes through the transparent glass. Something to do.

(2) The surface of a conductive probe with a reflective surface is developed with color toner, and the amount of infrared light reflected from the surface is detected.

(3) A device that irradiates complementary color light from a light source that emits complementary color light to the surface developed with color toner, and detects the reflected light.

According to the detection device (1), the amount of transmitted infrared light changes depending on the density of the color toner, so the density of the color toner can be detected by detecting the amount of transmitted light, and the density of the color toner can be detected by detecting the amount of transmitted light. According to the detection device, since the amount of light reflected from the reflective surface of the conductive probe changes depending on the density of the color toner, the density of the color toner can be detected by detecting the amount of reflected light, and (3) According to the detection device (1), the concentration of color toner can be detected by detecting the amount of complementary color light absorbed by the color toner. Since the light emitting elements are arranged, it is difficult to arrange them in a limited space, and according to the detection device (2), the color toner has a high reflectance in the infrared region (the amount of light reflected from the reflective surface itself is (the difference is small), there is a limit to the improvement of detection accuracy,
Furthermore, according to the detection device (3), it is necessary to prepare a light source according to the type of color toner.
This will lead to an increase in costs.

(Objects and Structure of the Invention) The present invention has been made in view of the above, and in order to prevent an increase in size and cost, and to improve detection accuracy, the present invention has been made to improve the detection accuracy by detecting reflected light of infrared light irradiated on color toner. The present invention provides a color toner density detection device for a copying machine that detects the density of color toner based on the following.

Hereinafter, the color toner density detection device for a copying machine according to the present invention will be explained in detail.

(Embodiment) FIG. 1 shows the structure of a color electronic copying apparatus, in which a developing device 2 (to be described later) (a developing device 2 (to be described later) (a green, blue, and red color filter 3 to be described later) surrounds a photoreceptor drum 1. Developing machine 2 for magenta, yellow, and cyan color toners corresponding to the colors
a, 2b, 2c), a charging corotron C, an exposure slit S, a transfer drum T, a cleaner K, etc. are arranged, and the above-mentioned color filter 3 is provided below the platen P on which the original is placed. An optical system O is provided, and a fixing device H is further arranged downstream of the transfer drum T. FIG. 2 shows one of the developing devices 2, which is installed opposite to the photoreceptor drum 1, and has a magnetic brush 5a formed therein to apply toner to the photoreceptor drum based on the developer 8 that has been conveyed. A developing roll 5 that is applied to the drum 1 to perform a developing action.
, a developer conveying roll 6 that conveys the developer 8 to the developing roll 5, a bristling regulation plate 7 regulating the height of the magnetic brush 5a, and a buffing regulation plate 7 that controls the development roll 5.
A developer transport plate 9 that transports the developer 8 that has been further peeled off into the developer housing 2a, and a developer scraping plate 10 that scrapes off the developer 8 that has been developed from the development roll 5 are installed. In addition, the developing roll 5
Above the roll-shaped conductive probe 11, which will be described later.
An infrared light receiving section 12, which will be described later, is provided above the conductive probe 11.

FIG. 3A shows an embodiment of the present invention, in which the surface of the conductive probe 11 is coated with a black coating 11a (for example, black sulfuric acid anodizing treatment), and a part of it is embedded with a permanent magnet 11b. . The infrared light receiving section 12 located above is a light emitting element 12 that emits infrared light toward the surface of the conductive probe 11.
a (for example, GL514 manufactured by Sharp Co., Ltd.) and a light receiving element 12 that receives reflected light from the conductive probe 11.
b (for example, PT550 manufactured by Sharp Co., Ltd.), and the light receiving and emitting elements 12a and 12b have an aperture 1 that adjusts the amount of light.
3a and 13b are provided. Infrared light receiving section 1
2 is a conductive mask 1 that transmits infrared light at the bottom thereof.
It has 4. As shown in FIG. 3B, the conductive mask 14 includes a transparent member 15 (for example, transparent glass) polished in a concave shape so that the central portion thereof has a curvature R concentric with the rotation center axis of the conductive probe 11. , a light-transmitting conductive member 16 provided on the surface thereof.

Figure 4 shows a conductive probe 11 and a conductive mask 1.
4 conductive member layer 16, a power supply circuit 20 that applies voltage to the developing roll 5, and a light emitting element drive circuit 2.
The controller 17 is an input interface 17 that inputs sensor signals or operation command signals from various sensors in the copying machine (not shown) or a console (not shown).
a, a ROM 17b that stores programs necessary for arithmetic processing of input signals, a CPU 17c that performs predetermined calculations based on the program, a RAM 17d that temporarily stores calculation results, data, etc., and a ROM 17b that stores programs necessary for calculation processing of input signals; It has an output interface 17e that outputs control signals to various control objects of the machine (not shown) or to a display section of a console (not shown). The power supply circuit 20 includes a development/cleaning power supply 18 that applies a square wave voltage to be described later to the conductive probe 11, a development roll power supply 19 that applies a predetermined voltage to the development roll 5, and a conductive material layer of the conductive mask 14. It has a conductive mask cleaning power supply 22 that applies a cleaning voltage to the mask 16.

To explain the operation of the above configuration, as shown in FIG. 2, the photosensitive drum 1 on which an electrostatic latent image is formed rotates clockwise, the developing roll 5 rotates counterclockwise, and the developing roller 5 rotates counterclockwise. A magnetic brush 5a is formed on the roll 5. The height of the magnetic brush 5a is regulated by a bristling regulating plate 7, and the magnetic brush 5a comes into contact with the photosensitive drum 1 to perform development. The developer 8 that has completed development is scraped off by a developer scraping plate 10, collected in the developing machine 2, and stirred, then conveyed to the developing roll 5 by the conveying roll 6, and then transferred to the developing roll again. A magnetic brush 5a is formed around the magnetic brush 5. The magnetic brush 5a contacts a conductive probe 11 placed above the developing roll 5.

The color toner density detection operation will be described below.

When an alternating current square wave shown in FIG. 7 is applied to the conductive probe 11, for example, when a positive voltage _V1 different from that of negatively charged color toner is applied for a time _t1 , the conductive probe 11 becomes conductive. Color toner is attracted to the surface of the probe 11 and developed, and when a negative voltage V ₂ of the same polarity as the color toner is applied for a time t ₂ , the adsorbed color toner is separated and cleaned. . As mentioned above, the light emitting element 12a is made of GL514, and when it emits infrared light having the spectral distribution shown in FIG. incident on . Light receiving element 12b
As mentioned above, it consists of PT550, and the fifth
The light-emitting element 12 as shown in Figure 2 shows the spectral sensitivity.
It is possible to detect light of 900 to 1040 nm emitted by a. The spectral reflectance of yellow, magenta, and cyan color toners is 900 to 1040 nm as described above when the background is black, as shown in Figure 6 A, B, and C.
The density of color toner in the infrared light region a,
Values corresponding to b, c (a>b>c) are shown. By the way,
In the case of black toner, the spectral reflectance is determined by toner concentrations a, b, c (a>b>
c) is a constant and low value regardless of When the conductive probe 11 is developed by the voltage V ₁ described above, reflected light corresponding to the density of the developed color toner enters the light receiving element 12b, while the voltage V ₂ described above
When the conductive probe 11 is cleaned by the black surface 11a of the conductive probe 11, the amount of light received by the light receiving element 12b is reduced.

Figure 8 shows the photoelectrically converted output based on the amount of light received by the light receiving element 12b, and when the envelope of the output waveform is taken, the maximum value V _i determined by the color toner density during development and the conductivity during cleaning. sex probe 1
The minimum value determined by the reflection of the black surface 11a of 1
Get V ₀ . Once the levels V _i and V ₀ of this output signal are determined, the toner density is detected from the ratio of the levels V _i and V ₀ for each color toner of yellow Y, magenta M, and cyan C, as is clear from FIG. can do.

Incidentally, a permanent magnet 1 is attached to a part of the conductive probe 11.
1b is embedded and a part of the developer 8 adheres to the permanent magnet 11b, so the conductive probe 11
Each time the permanent magnet 11b rotates, the developer 8 on the permanent magnet 11b comes into contact with the conductive mask 14 and cleans the surface of the conductive mask 14. Furthermore, since the center of the conductive mask 14 is formed in a concave shape with a curvature R concentric with the rotation center axis of the conductive probe 11, the contact state between the developer 8 on the permanent magnet 11b and the conductive mask 14 is maintained. This makes it possible to improve and even out the cleaning characteristics of the conductive mask 14, and furthermore, since a voltage of the same polarity as the color toner is applied, adhesion of the color toner is prevented. Next, even if the surface of the conductive mask 14 should become contaminated with color toner, the output angle of the light-emitting element 12a should be increased and the incident angle of the light-receiving element 12b should be increased, as shown by the dotted line D in FIG. 3A. Therefore, since the incident angle of the disturbance light generated on the surface of the conductive mask 14 is increased, and the incidence angle of the light receiving element 12b is increased, the incidence of the disturbance light generated on the surface of the conductive mask 14 is reduced. I can do it.
Further, apertures 13a and 13b are installed in front of the light emitting element 12a and the light receiving element 12b to adjust the amount of incident light and the spread angle of the incident light, so that together with the above-mentioned configuration, the incidence of disturbance light is further reduced. be able to. Furthermore, since the focal points of the light receiving and emitting elements 12a and 12b are set at positions deeper than the surface of the conductive probe 11, it is possible to reduce the incidence of disturbance light due to the gloss of the black coating 11a.

(Effects of the Invention) As explained above, according to the color toner density detection device for a copying machine according to the present invention, the density of the color toner is detected based on the reflected light of the infrared light irradiated by the color toner. It is possible to improve detection accuracy without causing an increase in size or cost.

[Brief explanation of the drawing]

FIG. 1 is a structural explanatory diagram of a color electronic copying apparatus. FIG. 2 is an explanatory diagram of the internal structure of the developing machine. FIG. 3A is a structural explanatory diagram of a conductive probe and an infrared light receiving/emitting section. FIG. 3B is a structural explanatory diagram of a conductive mask. FIG. 4 is an overall explanatory diagram of a color toner density detection device according to the present invention. Figure 5A is a spectral distribution diagram of the light emitting device (GL514). Figure 5 (b) is a spectral distribution diagram of the light receiving element (PT550). Figure 6 A, B, C, and D are graphs showing the spectral reflectance of color toner when the background is black (A is yellow, B is magenta, C is cyan,
d is black). FIG. 7 is an explanatory diagram showing a voltage waveform applied to a conductive probe. FIG. 8 is an explanatory diagram showing the output waveform from the light receiving element. FIG. 9 is an explanatory diagram showing the relationship between the amount of development of color toner obtained in this apparatus and the output of the light receiving element. Explanation of symbols 1... Photosensitive drum, 2... Developing machine, 2a... Magenta color developing machine, 2b...
Yellow color developing machine, 2c...Cyan color developing machine, 3...Color filter, 5...Developing roll, 5a...Magnetic brush, 6...Developer transport roll, 7...Standing regulation plate, 8 ...Developer, 9...
Developer transport plate, 10...Developer scraping plate, 11
... Conductive probe, 11a ... Black coating, 11b ... Permanent magnet, 12 ... Infrared light receiving and emitting section, 12a ... Light emitting element, 12b ... Light receiving element,
13a, 13b... Aperture, 14... Conductive mask, 15... Transmissive member, 16... Conductive member, 1
7... Control unit, 18... Power source for developing/cleaning, 19... Power source for developing roll, 20... Power supply circuit, 21... Drive circuit, 22... Power source for conductive mask cleaning.

Claims (1)

[Scope of Claims] 1. In a color toner density detection device for a color copying machine that detects the toner density of a color copying machine based on the amount of infrared light reflected from the color toner, the rotating body has an absorption surface that absorbs infrared light. and,
an electric field applying means for attaching color toner to the absorption surface of the rotating body based on a predetermined timed detection cycle; a light emitting element for irradiating infrared light to the color toner attached to the absorption surface of the rotating body; A color toner concentration detection device for a copying machine, comprising: a light receiving and emitting means comprising a light receiving element that receives reflected infrared light from the color toner in an amount corresponding to the toner density.