JPS6083975A - Toner concentration controller - Google Patents

Abstract

PURPOSE:To control the toner concn. with only a photosensor to improve the image quality by controlling a toner supply member on a basis of the black level and its width of a pattern image formed on the surface of a photosensitive body in accordance with a reference pattern consisting of black parts and white parts. CONSTITUTION:A reference pattern image 3 formed on the surface of a photosensitive body 2 is detected by a photosensor 1a to output a pulse signal corresponding to stripes of the pattern. A microcomputer 1d reads output signals of the photosensor 1a and an integrator 1c at the first fall time point of this pulse signal and detects a black level and a black width of the reference pattern. The toner supply member is controlled on a basis of this detection result, and thus, the toner concn. is controlled in consideration of the thickness of the image in addition to the image density by only the photosensor to obtain high-quality copies.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a toner concentration control device for a two-component developer in an electronic 5J device.

(Prior art) The toner density of a two-component developer consisting of toner and carrier is controlled by a P sensor that forms a reference density pattern image outside the image forming area of the photoreceptor drum and detects the optical g of this pattern image. However, as shown in Fig. 2, when the toner value 1i exceeds a certain value, the image density becomes saturated and toner is supplied regardless of the toner level. There is a problem in that the line drawing becomes thicker and the copy quality deteriorates.

In order to solve this problem, we integrate not only the P sensor signal but also the signal from the F sensor, which detects toner density from changes in the inductance of an inductance element installed in the development unit, to determine the image density and development. The toner replenishing member has been controlled in consideration of the toner concentration in the toner.

For this reason, there was a problem in that two types of detectors, the P sensor and the F sensor, were used for 8 degrees, making maintenance and adjustment troublesome.

(IEI-like) In view of such problems, it is an object of the present invention to provide a novel control device that can control toner to an optimal density using an F sensor.

(92 bright configuration) That is, the feature of the present invention is that, as shown in FIG. pattern image detection means for outputting a pulse signal proportional to the degree of the image, black level detection means for detecting the black level from the level of the pulse signal, and black width detection means for detecting the black width from the pulse width. and a toner replenishing member control means for operating the toner replenishing member based on the black level and black width detected by these means.

(Embodiment) Therefore, an explanation will be given below based on an embodiment of the present invention in which the iT details are reduced.

FIG. 1 shows a smaller version of one embodiment of the present invention, and reference numeral 1 in the figure indicates a toner density control device which forms part 411Φ of the present invention. A photosensor la detects the basic density pattern image 3 formed on the surface of the body drum 2 and outputs a pulse signal proportional to the width of the IR melon in the black part, and an inverter ib converts the signal from the photosensor la. an integrator 1c that inverts and integrates this and outputs a signal proportional to the width of the black part;
The rising time of the signal from the photosensor 1a is used as the signal) to detect the black level and black width based on the output from the integrator 1c and the signal from the photosensor 1a. The image forming apparatus is composed of an operating microcomputer ld.The reference numeral 4 in the figure indicates a developing unit disposed around the photosensitive drum.

FIG. 4 shows a smaller example of the reference density pattern described above, in which black stripes B with a predetermined width W are arranged at regular intervals, and these are placed outside the contact crow or By disposing it in, for example, a filter in the optical path of the optical system, it is configured to form a black and white pattern image (FIG. 5) in the circumferential direction outside the document forming area of the photoreceptor drum.

Next, the operation of the apparatus configured as described above will be explained in flowchart 1 and 2 shown in FIG.

When the electronic main body is operated, a reference pattern is exposed on the surface of the photoreceptor drum 2 to form a latent image, which is developed by the developing units 1 and 4 to form a reference pattern image 3. This ), (hetero pattern image 3 moves to the detection area of the photosensor la as the photosensitive drum 2 rotates and is detected, and a pulse-like 4?- corresponding to the striped pattern of the pattern is detected.
``J outputs (Fig. 7B). At the first f edge of this pulse I, the microcomputer ld reads the outputs from the photosensor la and the integrator 1c, and calculates the reference pattern. Detects the black level and black width.If the toner density is maintained normally, the seventh
As shown in Figure (I), since the black level and black width of the base pattern image each match the set value, the toner replenishing member is not operated. If you continue copying in such a situation, the toner will be consumed and the toner concentration in the developer will decrease, the image density of the black part of the reference pattern image will decrease, and the signal level will decrease. Setsummer 4r
i, the microprocessor 1d activates the toner replenishing member to start toner replenishment and raise the toner concentration in the developer. As a result, the black color of the reference pattern image
Does the image density in the □ area increase and the signal level decrease?
The toner concentration in the developer has not yet reached the appropriate value, the image becomes thinner, the black width falls below the set value, and toner replenishment continues. When the toner density reaches a predetermined value, the black width exceeds the set value, so the operation of the toner replenishing member is stopped and toner replenishment is stopped (II)
. Thereby, a clear copy of the line drawing with a specified image density can be obtained.

In addition, if the image density does not increase due to problems with the charging unit I, etc., and the black level exceeds 1-dead density, the pattern becomes thicker as toner is replenished and the black width exceeds the set value. Stop the replenishment member and replenish toner to prevent excessive toner supply (m). Furthermore, even when the image density has reached m = constant value,
If the image is thin due to low toner density, the black width will be the same as the set value, so replenish I/toner until the black width reaches the set value to prevent the image from thinning 11-
do.

In addition, in this embodiment, 4
The black width of the reference pattern image was obtained by integrating tj ``j, but the pulse width of one black pattern can be directly calculated by a+
A similar effect can be obtained even if the lI is set.

(Efficacy) As explained in 1-1, in the present invention, a striped reference pattern formed of black and white parts is used, and the black level of the pattern image formed on the surface of the photoreceptor drum and its Since the toner replenishing member is controlled based on the width, the toner density can be controlled using only the P sensor, taking into account not only the deviation of the image but also the fatness and thinness of the image, resulting in high-quality copies. Obtainable.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, and FIG. 2 is a block diagram showing the configuration of the present invention.
Figure 3 is an explanatory diagram showing the relationship between the toner old landing place and the image density, and is a professional diagram of the apparatus embodying the embodiment of the present invention.
FIG. 14 is a small two-view diagram of one embodiment of the reference pattern;
Fig. 5 is a perspective view showing the semi-pattern image, Fig. 6 is a flowchart I explaining the operation of the same 1-. device, and Fig. 7 is a waveform diagram showing the operation of the same 1- device. 1...Toner density control device 1a...Photo sensor lb...Innoparter lc...) Crystal content g4 1d...Microcomputer 2...Photoconductor driver 11 3... base? ll/Density pattern image Applicant: Co., Ltd. 1 Ricoh - Agent: Br. Keiji Nishikawa Katsuhiko Kimura 1st figure 2nd figure A' wear amount figure 3rd figure 4th page 5th page

Claims (1)

[Claims] means for forming a reference pattern image consisting of a black part and a white part on the surface of a photoreceptor drum; a pattern image detection means for outputting a pulse signal proportional to the density of the black part and its width while scanning the pattern image; and the pulse signal. black level detection means for detecting the black level from the pulse level of the signal; black width detection means for detecting the black width from the pulse width of the pulse signal;
and toner replenishment member control means for operating a toner replenishment member based on the black level and black width detected by the means.