JPS6045278A - Toner concentration control device - Google Patents

Abstract

PURPOSE:To always hold a normal concn. of a color toner by comparing a ratio of a voltage converting value of a reflected light by a variable density of a basic original pattern image, with a set value determined by a color of a developer. CONSTITUTION:If a value of a ratio V1/V2 of a reflected light voltage converting value V1 of a light part of a basic original pattern image 19 and the same value V2 of a dark part is the same as a value C set in advance, namely, in case of V1/V2=C, it is normal, and in case of V1/V2>C, it is a high density, and no toner is supplied, and on the other hand, in case of V1/V2<C, it is a low density, and a toner is supplied. When a color of a developer is varied, the reflection factor is varied, and the values of V1, V2 are varied. Accordingly, a toner concn. of a developer of each color can be held normally by utilizing said point and varying a value of the set value C compared with V1/V2 in accordance with a color of the developer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner density control device in an electrophotographic copying apparatus or the like which attempts to obtain copied images in five different colors.

Good Smelling Leather 4 When trying to obtain copied images of different colors, it is necessary to change the toner concentration control since the toners are of different colors, but it has not been possible to perform simple and effective control.

Replace multiple developing units containing one color of developer,
Alternatively, in copying machines and the like that can select from a plurality of images to obtain images with different colors, toners of different colors are used, so it is necessary to change the toner density control. Performed by switching the control, multicolor 1
- attempts to maintain appropriate concentration of the toner.

Figure 1 of 1 is a cross-sectional view showing the structure around the photosensitive drum of an electrophotographic copying apparatus. The color of the image can be changed by replacing the unit, and Fig. 2 is similar to Fig. 1, but it is possible to select from multiple developing units containing developers of different colors. The color of the image can be changed by developing it.

In FIG. 1, a charger 2 is placed around the photoreceptor drum 1.
, an exposure device 3, a replaceable developing unit 4, a density detection sensor 7 consisting of a light emitting diode 5 and a reflected light receiving element 6.
, a transfer paper guide 8, a transfer separation charger 9, a separation claw 10, a cleaning unit 11, etc. are provided. In addition, 1
2 is an erase lamp.

FIG. 3 is a diagram showing a part of the exposure device 3, in which a basic original pattern 15 having a binding part and a shallow part is provided on the back surface of the contact glass 14 on which the original 13 is placed near the original setting part. 15 is illuminated by an exposure lamp 16, and the reflected light is reflected and guided by a mirror 17 and the like to expose the photoreceptor drum j.

Figure 4 shows the principle of the concentration detection sensor mechanism.
A) is a plan view of the basic original pattern 15, and (B) is a plan view of the photosensitive drum 1. @Relationship between image drum 18, density sensor 7, and basic original pattern image 19, (c) is density detection sensor 7
This is a diagram showing the relationship between the output of the scanner and the position of the basic original pattern 15. When the density detection sensor 7 reads the shading of the basic original pattern image 19 exposed on the photoreceptor drum 1 and developed by the developing drum 18, The reflected light voltage conversion value Vl of the shallow part is high, and the output voltage v2 of the forming part is low, but the value changes because the intensity of the reflected light differs depending on the level of toner concentration.

Utilizing this, the ratio V
, /V2 is the same as the preset value C, that is, V
, /V2=C, then proper concentration, V+ / V2 > C
If so, there is no toner replenishment because the density is high, ■r/Vz<
If it is C, the density is low, so toner is replenished.

However, when the color of the developer changes, the basic original pattern image is developed with the color of the developer, and even if the density is appropriate, the reflectance differs depending on the color. During development, (c) yellow development, the values of Vl and V2 change.

In the present invention, taking advantage of this point, the toner concentration of each color developer is changed by changing the value of the set value C compared with V and /V2 according to the color of the set developer. This enables the maintenance of proper conditions. That is, in the embodiment shown in FIG. 1, when the developing unit 4 is replaceable and an image of a different color is to be obtained, the developing unit is replaced with a developing unit containing toner of the desired color, and at the same time, Try changing the setting value C. In the embodiment shown in FIG. 2, a plurality of developing units 4.4', 4'' are provided, and only the developing unit of a desired color is operated, and the setting value C of the color to be operated is set. By changing the developer density, the developer can always be maintained at an appropriate 1-toner concentration, so even when copying different colors, the optimum copy can always be obtained.

6(a) and 6(b) are flowcharts of an embodiment according to the present invention, and FIG. 7 is a circuit diagram thereof.

According to the present invention, the appropriate density of color toner is always maintained by comparing the ratio of the voltage conversion value of reflected light depending on the density of the basic original pattern image with a set value determined depending on the color of the developer. This makes it possible to always obtain copies with optimal colors.

Note that changing the setting value C requires replacing the developing unit,
Alternatively, the switching may be performed automatically at the same time as the switching of the active developing unit, or may be performed manually each time.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing the arrangement around the photoreceptor drum equipped with a replaceable developing unit, Figure 2 is a diagram similar to Figure 1 showing the case with multiple developing units, and Figure 3 is the basic FIG. 4 is a cross-sectional view showing the installation state of the original pattern, and is an explanatory diagram of the toner density control mechanism based on the basic original pattern.
is a plan view of the basic original pattern, (b) is a diagram showing the reading state of the developed basic original pattern image by the density detection sensor, and (c) is a diagram showing the shading position of the basic original pattern image and the voltage conversion value of its reflected light. Figures 5 (a), (b), and (c) show the relationship between the grayscale position of the basic original pattern image and the voltage conversion value of the reflected light for black development, red development, and yellow development, respectively. FIGS. 6A and 6B are flowcharts of an embodiment of the present invention, and FIG. 7 is a circuit diagram thereof. l... Photosensitive drum, 3... Exposure device, 4, 4
', 4''...Development units 1-.7...Density detection sensor, 13...Original, 14...Contact glass, 15...Basic original pattern, 16...Immediate lamp, 18... ...Developing drum, 19...Basic original pattern image, vl, v2...Voltage conversion value of reflected light, C...
・Setting value depending on developer color. Agent Patent Attorney Makoto Kon

Claims (1)

[Claims] When developing a latent image formed on a photoconductor by a two-component development process using carrier and toner, it is necessary to replace multiple developing units containing different colored developers or to change the number of installed developing units 1-1. In an electrophotographic copying device that obtains images with different colors by selecting one of the following, the developed density of a basic original pattern with shading on the photoreceptor is read by the amount of reflected light, and each of the shading images is When controlling the toner density by comparing the ratio value of the reflected light with a predetermined value, the set value to be compared with the ratio value of the reflected light is set according to the color of each developer. A toner concentration control device characterized in that the developer concentration of each color can be controlled by switching.