JPS6057869A - Toner density measuring device for color electrophotography - Google Patents

Abstract

PURPOSE:To measure toner density while each developer is held sufficiently in the hopper of a detector by detecting toner density in the order of developing colors after development of three primary colors is performed. CONSTITUTION:When development is started in the order of yellow, magenta, and cyan during copying operation, toner is deposited in toner density detectors 5Y, 5M, and 5C in the order of developing units 1Y, 1M, and 1C. A CPU8 after detecting the completion of the development of the final color, i.e. cyan turns on the 1st multiplexer 7Y to receive the signal from the toner density detector 5Y for the 1st primary color, i.e. yellow, and compares it with a set value to operate a toner supplementing member, controlling the toner in a yellow developing unit 1Y to constant densty. Similarly, said procedure is repeated in the order of magenta and cyan to measure and control the toner density while the developer is supplied to the detectors 5Y, 5M, and 5C of the respective developing tanks.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a toner concentration detection means δ for a color electrophotographic apparatus.

(Prior Art) A color electrophotographic device that uses a two-component developer consisting of toner and carrier has three developing units each containing yellow, magenta, and cyan toners, as shown in Figure 1. lY, IM, IC to photoreceptor drum 2
The latent image formed by color separation of a color document is developed in the order of yellow, magenta, and cyan, and the toner density of the developing units 1Y, 1M, and IC is managed by the developing sleeve 3Y, Toner concentration detectors 5Y and 5M each include a hopper having a coil wound around a separate lake 4Y, 4M and 4C that are in contact with 3M and 3C.

5C is provided, and this is used as an inductance element to configure an LC oscillator to measure the toner concentration as a frequency.

Conventionally, the toner concentration of such a color electrophotographic apparatus was measured immediately after the development of each light color was completed, as shown in FIG. 6, so that the developer on the separator had a sufficient toner concentration. There was a problem in that it did not flow into the detector, causing errors in measurements.

(Objective) In view of such problems, an object of the present invention is to provide a toner detector with high measurement accuracy.

(Structure of the Invention) That is, the feature of the present invention is that, as shown in FIG. The toner density signal is sampled through the toner density signal capturing means, and the toner density is measured when the developer is sufficiently accumulated in the toner density detector.

(Example) Therefore, an explanation will be given below based on an example illustrating a 3-T thin structure of the present invention.

FIG. 2 is a configuration diagram of an apparatus showing an embodiment of the present invention, in which reference symbols 6Y, 6M, and 6C indicate toner concentration detectors 5Y, 5M, and 5C provided in each developing tank. The first, second, and
It is configured to output an oscillation frequency signal proportional to the toner concentration of the developer to the data bus in 11+j divisions via the third multiplexers 7Y, 7M, and 7C. 8 is a CPU that detects the point in time when the development process for all light colors is completed, and first to third multiplexers 7Y.

7M and 7C are configured to operate in sequence.

Next, the operation of the apparatus configured as described above will be explained based on flowchart 1 shown in FIG.

Now, when the copy button is pressed, the CPU 8 detects this and turns the multiplexer OFF to prevent the output signals from the LC oscillators 6Y, 6M, and 6C from being input to the CPU 8. At the same time, the copying operation for the first sheet starts, and development begins in the order of yellow, magenta, and cyan.
Sleeves 3Y and 3M of each developing unit IY, IM, and IC
, 3C via separators 4Y, 4M, 4C to toner density detectors 5Y, 5M, 5C in order (Fig. 5 ■), and develops yellow, magenta, and cyan. Toner concentration detectors 5Y, 5M, and 5C accumulate in the toner density detectors 5Y, 5M, and 5C of the unit II. The first multiplexer 7Y is turned ON, the signal from the toner concentration detector for the first light color, that is, yellow, is captured, compared with a set value, and the toner replenishing member is operated, thereby producing the yellow developing unit.

1. Control the IY toner concentration to a constant level. Next, the second multiplexer 7M is activated to receive the magenta toner density signal, and the third multiplexer 7C is activated to receive the cyan toner density signal and compared with the setting A16 (Fig. 5). II). As a result, the toner concentration can be controlled by adding N to 11 in a state where the detectors 5Y, 5M, and 5C of each developing tank are filled with developer.

(Effects) -1 As explained above, according to the present invention, the toner concentration is detected in the order of the developed colors when the development of the three light colors is completed. The toner concentration can be measured when the developer is sufficiently accumulated, and there is no risk of 11111 error due to excess or deficiency of developer.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a developing unit of a color electrophotographic apparatus, FIG. 2 is a block diagram showing the configuration of the present invention, and FIG. 3 is a block diagram of the apparatus showing an embodiment of the present invention. , FIGS. 4 and 5 are the same flowchart and timing diagram showing the operation of the apparatus, and FIG. 6 is a timing diagram illustrating the operation of the conventional system. IY, IM, IC...Developing unit 2...Developing drum 5Y, 5M, 5C...I-ner density detector 7Y, 7
M, 7C...Multiplexer Applicant Ricoh Co., Ltd. Agent Patent Attorney Yoshie Nishikawa Katsuhiko Kimura Figure S Figure 6I121

Claims (1)

[Claims] In a color electrophotographic apparatus that sequentially performs development using light color toners, a toner concentration detection means detects the toner density of each light color, and a developing device detects the point in time when the development process of all light colors is completed and outputs a signal. I/Toner density A1 for color electrophotography, characterized in that it comprises a process detection means, and a toner concentration signal capture means for capturing signals from the toner density detection means for each light color in the order of development based on the signals from the means. Fixed device.