JPH08152776A - Toner concentration controller - Google Patents

Abstract

PURPOSE: To precisely control a toner concentration without considering a mechanical and electrical change, even in the irregular fluctuation of an analog signal detected by a toner concentration sensor and the toner concn. with a simple change even in a change in design. CONSTITUTION: This toner concentration controller is provided with a comparator 52 comparing an analog signal for showing the state of a toner quantity detected by the toner concentration sensor 10 with the reference signal of a constant voltage, and converting into a rectangular wave signal, a pulse width detecting means 53 detecting the pulse width of the converted rectangular wave signal, and an arithmetic processing part 55 using plural bits of information of the pulse width detected by the pulse width detecting means 53, to calculate an operation value with an operation for averaging, difference and addition, and constituted to control the supplying of the toner based on the operation value processed by the arithmetic processing part 55.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner density control device for detecting the ratio of toner itself or a toner in a developer consisting of toner and a magnetic carrier by optical and magnetic permeability changes, and more particularly to a toner density sensor. The present invention relates to a toner concentration control device capable of highly accurate toner concentration control even if an irregular signal of the detection signal is generated.

[0002]

2. Description of the Related Art Conventionally, in a two-component developing system, for example, a change in the mixing ratio of the toner and the magnetic carrier has a great influence on the image quality and the like, so that it is necessary to keep the mixing ratio constant. A method has been proposed in which the toner density is recognized based on the change of the toner and the toner is replenished (JP-A-2-64560, JP-A-2-93568). Particularly, in Japanese Patent Laid-Open No. 2-64560, a vibration wave obtained by stirring the detection sensor surface with a stirring blade is superimposed on an analog signal obtained by replenishment control by a sensor that detects the developer passing through the magnetic permeability sensor surface. After forming a detection signal and comparing the detection signal with a reference signal corresponding to a predetermined toner concentration level (hereinafter, referred to as “threshold”) and converting into a square wave corresponding to the positive or negative of the difference, It is disclosed that precise density control is performed by supplying only the converted pulse width.

[0003]

However, in the apparatus for controlling the density by changing the magnetic permeability sensor, the T / C (toner / carrier) of the developer, the volume of the developing container, the stirring member, etc. are changed by the design change. Alternatively, it is known that the output waveform shape of the detected analog signal changes due to the change in the fluidity of the developer due to the change in the particle size of the developer.

Therefore, if this change is too large,
The data before the change became unusable, and even if the applicable range was decided once, the electrical change of the threshold and the shape change of various constituent members could only be found and adapted for each design change. The reason for this is that the magnetic permeability sensor controls the toner concentration by capturing the change in magnetic permeability, and in addition to magnetic permeability, physical and chemical changes are complicatedly related between the toner and the magnetic carrier. It is thought that this is because there are many.

Such a conventional technique will be described with reference to FIG.
FIG. 7 is an explanatory diagram for detecting a conventional toner concentration, A is an output waveform before a design change by a toner concentration sensor (not shown), and B is a shape of a mixer (not shown) for mixing toner and carrier. The output waveform generated when In addition, C is the threshold before design change,
A'and B'are the output signals of A and B and the threshold C.
Are compared to form a rectangular wave signal corresponding to the time when the threshold C is exceeded, where A ′ is before change and B ′ is before change.
Indicates the one after the change. Where 0N of the square wave signal
The pulse signal width is set to be the toner replenishment time.

Here, when the toner density changes to high or low, the amplitude and cycle of the analog signal in FIG. 7 hardly change, and the analog signal moves up and down with reference to the threshold C (not shown). Become. Therefore, the pulse width of the rectangular wave signal changes corresponding to the change of the analog signal,
The replenishment time will also increase or decrease according to the change.

However, when the shape of the mixer is changed, an irregular waveform D, which is different from the waveform A before the change,
E is formed and converted to a different toner replenishment time. Therefore, if it is used as it is, excessive supply,
Since the toner density cannot be precisely controlled due to insufficient replenishment or the like, it is necessary to electrically change the above-mentioned threshold, particularly to change the time constant of the circuit provided in the toner density sensor.

As a countermeasure against such a case, it is conceivable to form a flow path of the developer flowing on the detection surface of the toner concentration sensor so as to suppress the fluctuation of the analog signal as much as possible so that a constant fluidity is obtained. However, the detection structure of the toner concentration sensor becomes complicated, and it may be difficult to adopt such a structure as the developing device becomes smaller.

The present invention has been made in view of the above-mentioned drawbacks, and it is possible to prevent mechanical fluctuations due to irregular fluctuations of analog signals.
It is an object of the present invention to provide a toner density control device that can accurately control toner density without considering electrical changes and that can easily control toner density even in design changes.

[0010]

In order to solve the above problems, the present invention performs toner replenishment control based on a toner replenishment signal detected by a toner concentration sensor so that a preset toner concentration is obtained. In the toner concentration control device,
By comparing an analog signal indicating the state of the toner amount detected from the toner concentration sensor with a reference signal of a constant voltage,
Converting means for converting into a rectangular wave signal corresponding to the positive or negative of the difference, pulse width detecting means for detecting the pulse width of the rectangular wave signal converted by the converting means, for example, as a digital signal or a time signal, and its pulse width An arithmetic means for calculating an arithmetic value by a predetermined arithmetic operation using a plurality of pulse width information detected by the detecting means is provided, and toner replenishment control is performed based on the arithmetic value of the arithmetic means.

The calculation means in this case may be a calculation means for averaging a plurality of pulse width information, and an addition means for adding a plurality of pulse width information and the addition value and a preset value. The comparing means may be configured to compare, and further, the calculating means is based on two consecutive pulse width information among the plurality of pulse width information converted by the converting means,
It is also achieved by using a subtraction unit that calculates the difference (absolute value) of the pulse width information.

[0012]

According to the above construction, the analog signal corresponding to the change in magnetic permeability is converted into a rectangular wave signal to obtain the pulse width,
Calculations (averaging, addition, subtraction) are performed using a plurality of rectangular wave signals, the detection error is reduced as much as possible, and the toner replenishment time is controlled by the calculated values, whereby irregular changes in the analog signal, Absorb variations sufficiently.

[0013]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic explanatory view of a developing device according to an embodiment of the present invention. Specifically, reference numeral 1 is a developing device in which a ratio of carrier and toner is set to a target density and accommodated, and a photosensitive drum. 4, a developing sleeve 3 containing a mag roll 3a is rotatably supported on the opening side, and a toner container 2 is mounted above the developing device 1 via a partition plate 5.

Further, a tapered concave portion 6 is formed at a predetermined position of the partition plate 5 so as to extend in the rotation axis direction of the developing sleeve 3, and the slit opening 6 is formed on the bottom side of the concave portion 6.
a is provided, and the toner supply roller 7 in which a sponge is wrapped is rotatably attached to the recess 6. A motor 8 for rotating and a drive circuit 9 for controlling the rotation drive thereof are connected to the supply roller 7.

Reference numeral 11 denotes a known single-vibration mixer, which is installed immediately below the slit opening 6a, and a plurality of circular stirring plates 23 centering on a shaft 21 are inclined at a predetermined angle and are parallel to each other in the axial direction. It is formed, whereby the developer is agitated. Further, a toner concentration sensor 10 that faces the outer periphery of the stirring plate 23 of the single-vibration mixer 11 on the side surface of the developing device 1 and detects a change in the mixing ratio of the magnetic carrier and the toner as a change in magnetic permeability is installed. Only the detection surface 10a of the toner concentration sensor 10 is exposed to the inner surface of the developing device 1, and the vibration generated on the detection surface 10a by stirring the simple vibration mixer 11 is captured as an analog signal. Is transmitted to the control circuit 50.

The control circuit 50 is constructed by the block diagram shown in FIG. Hereinafter, description will be given with reference to the drawings. Reference numeral 52 is a comparator for comparing the analog signal from the toner density sensor 10 with the signal from the reference voltage generating means 51 for generating a threshold value and generating an ON-OFF pulse signal for toner density detection. Reference numeral 53 is a counter for counting the pulse width of the rectangular wave signal, which is detected as a digital signal. In addition, although the example in which the digital signal is detected is described in the present embodiment, the present invention is not limited to this, and the process of the present invention can be performed even if the time is detected.

Reference numeral 55 denotes an arithmetic processing unit for performing arithmetic operation using a plurality of rectangular wave signals corresponding to the pulse width output from the counter 53, and as shown in FIG. 5 or 6, RAM 55a or 55b for storing pulse width information. Is installed. Reference numeral 56 is a detecting means for detecting the signal level by sampling the arithmetically processed arithmetic value at regular intervals. 5
Reference numeral 7 denotes a treatment processing unit that performs a treatment process when the toner replenishment signal is continuously detected as a result of sampling by the detection unit 56, and sends a signal to that effect to the drive circuit 9. Here, the treatment process is a process of stopping the printing process and rotating the motor 8 for a certain period of time when the toner density is lowered and the printing density is affected.

Reference numeral 58 is a drive processing section for outputting a control signal to the drive circuit 9 based on the calculated value, and 61 is a signal detected by the detection section 56, and the level Hi continues to be output, and the set time of the timer 60 has passed. However, the toner empty detection unit indicates that there is no toner in the toner container 2 when the level Hi is continuously displayed.

Next, the contents of the arithmetic processing of the arithmetic processing unit 55 will be described. As the processing content, one of the following averaging, integration, and difference processing is performed. (Averaging Process) The routine of the arithmetic processing unit 55 starts after the simple vibration mixer 11 is rotated with the start of printing to detect the density. First, the pulse width of the rectangular wave signal is counted by the counter 53. The RAM 55 included in the arithmetic processing unit 55 shown in FIG. 5 has n addresses (Dg 1 to Dg 1
The pulse width information is sequentially written in n), and the average value (DgAVE 1) of the pulse width of the rectangular wave signal counted by the counter is calculated based on the pulse width information as shown in the following equation (1). DgAVE 1 = (Dg 1 + Dg 2 + Dg 3 ... Dg n) / n (1) Then, the memory of address Dg 1 is erased and the next waveform n +
The pulse width information of 1 is written in the address Dg 1, and the average value of the pulse width (DgAVE 2) is calculated based on the following equation (2).

DgAVE 2 = (Dg 2 + Dg 3 + Dg 4 ... Dg n + 1) / n (2) The above calculation is repeated to obtain each average value (DgAVE 1,2,3
...) is calculated. Replenishment is performed based on this average value.

(Integration) After the start of printing, the simple vibration mixer 11 is rotated to detect the density, and then the routine of the arithmetic processing section 55 is started. First, as shown in FIG. 3, the counter 53 writes the pulse width information into the n addresses of the RAM 55a shown in FIG. 5 (STEP1). Next, the addition value S of n pulse widths is calculated as shown in the following equation (3) (STEP 2). S = Dg 1 + Dg 2 + Dg 3 ... Dgn (3) Next, the arithmetic processing unit 55 compares the threshold value with a predetermined threshold value (STEP 3). , "Level Hi") is transmitted to the detecting means 56 (STEP4), and the process returns to STEP1. But S
If it is lower than the threshold in TEP3, a signal of level Lo is transmitted, and the process returns to STEP1 to repeat the control.

(Difference) After the start of printing, the simple vibration mixer 11 is rotated to detect the density, and then the routine of the arithmetic processing section 55 is started. As shown in FIG. 4, first, the pulse width information of two continuous rectangular wave signals is calculated by R in the arithmetic processing unit.
Write to AM55b (STEP5). Next, the subtraction value T of the pulse width written in the RAM 55b is calculated as shown in the following equation (4) (STEP6). T = | Dg 1−Dg 2 | (4) Next, compare with a predetermined threshold (STE
P7), and if the value exceeds that, a signal of level Hi (a signal that the toner is insufficient) is transmitted to the detection means 56 (S
Return to TEP8) and STEP5. But in STEP 7. However, if it is lower than the threshold, a signal of level Lo is transmitted and the process returns to STEP5 to repeat control.

[0023]

[Effect] As described above, the analog signal detected by the toner density sensor and the reference signal of a constant voltage are compared and converted into a predetermined rectangular wave signal, and a plurality of rectangular wave signals are calculated by the above calculation processing. In addition, since the toner is replenished based on the calculated value, the detection error of each signal can be reduced and controlled, and irregular changes and variations of the analog signal can be absorbed, resulting in mechanical and electrical It is possible to provide a toner concentration detection device that can accurately control the toner concentration without considering the change, and can easily control the toner concentration even when the design is changed.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an outline of a developing device of the present invention.

FIG. 2 is a block diagram of a toner concentration control device of the present invention.

FIG. 3 is a flowchart showing an integral calculation process of the toner concentration control device of the present invention.

FIG. 4 is a flowchart showing a difference calculation process of the toner density control device of the present invention.

FIG. 5 is a configuration diagram of a RAM in the arithmetic processing unit of the present invention.

FIG. 6 is a block diagram of a RAM in an arithmetic processing unit showing another embodiment.

FIG. 7 is an explanatory diagram of conventional toner density control.

[Explanation of symbols]

 1: Developing device 2: Toner container 3: Developing sleeve 10: Toner density sensor 11: Single vibration mixer 50: Control circuit 51: Reference voltage generating means 52: Comparator (converting means) 53: Counter (pulse width detecting means) 55 : Arithmetic processing unit (arithmetic means)

Claims (4)

[Claims] 1. A toner concentration control device for performing toner replenishment control so as to achieve a preset toner concentration based on a toner replenishment signal detected by the toner concentration sensor. Compare the analog signal that shows the state of quantity with the reference signal of constant voltage,
Converting means for converting into a square wave signal corresponding to the positive / negative of the difference, pulse width detecting means for detecting the pulse width of the rectangular wave signal converted by the converting means, and a plurality of pulses detected by the pulse width detecting means. And a toner density control device for performing toner replenishment control based on the calculation value of the calculation means. 2. The toner density control device according to claim 1, wherein the arithmetic means is an arithmetic means for averaging a plurality of pulse width information. 3. The toner according to claim 1, wherein the calculating means includes an adding means for adding a plurality of pieces of pulse width information and a comparing means for comparing the added value with a preset value. Concentration control device. 4. The subtraction means for calculating the difference (absolute value) of the pulse width information based on two consecutive pulse width information out of the plurality of pulse width information converted by the converting means. The toner density control device according to claim 1, wherein the toner density control device is provided.