JPH1054796A - Liquid concentration detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely measure toner concentration by correcting a measured liquid concentration with the measured value of the light quantity of the reflected or transmitted light when no liquid is present. SOLUTION: A developer 1 within a transparent tube 6 is lighted by an illuminating lamp 11, and the light transmitted by the tube 6 is detected by a photo transistor 13, thereby, the concentration of the developer in the tube 6 is optically read. A main body control part 20 loads a microcomputer 22 having an A/D input terminal 21, and the output signals of voltage amplifiers 15B, 15G, 15R are inputted to the A/D input terminal 21 of the microcomputer 22. Since the value of the voltage proportional to the light quantity of the photo transistor 13 is read from the A/D input terminal 21 of the microcomputer 22, the microcomputer 22 corrects the portion of light quantity reduction by the toner contamination 7 of the glass tube 6, and a precise change of developer concentration can be known.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid concentration detecting device, and more particularly, to a sensor for detecting the concentration of a developing solution, such as an analog color copying machine, a digital color copying machine, and a color printer, having a wet developing device. In Although,
More generally, the present invention relates to a general sensor for optically measuring the concentration of a liquid in a transparent container or a transparent tube.

[0002]

[Prior art]

When a visible image is formed by an electrophotographic apparatus or the like, a fixed ratio of toner and carrier are mixed in a developing device, and an electrostatic latent image on an image support, that is, a photoreceptor is developed with the developing solution. However, when the development is repeated, the amount of the toner contained in the developing liquid in the developing device decreases, so that the density of the visible image of the developing object decreases. In order to prevent such a phenomenon, it is necessary to supply toner to the developing device sequentially. However, since the amount of toner consumption is different depending on the area and density of the visible image to be created, the amount of toner in the developing device is reduced or the amount of toner in the developing device is too large, and the density of the developed visible image is constant. No longer.

Therefore, conventionally, various methods for measuring the concentration of a developing solution have been employed in order to control the toner concentration in the developing solution in the developing device to be constant. For example, a developer is allowed to flow into a glass tube, and a light-emitting element and a light-receiving element are arranged so as to sandwich the glass tube. By measuring a change in the amount of light transmitted through the developer, the ratio of the toner in the developer is measured. And replenish the toner shortage.

Conventionally, a color sensor has performed measurement using infrared light or monochromatic light. Color toners (Y: yellow, M: magenta, C: cyan) hardly absorb infrared light or monochromatic light other than complementary colors. for that reason,
Since the amount of transmitted light or the amount of reflected light does not change much depending on the concentration of the liquid, accurate measurement was difficult.

[0006]

The color image formation of a color printer or a color copier is performed by forming Y, Y on a drum on paper.
This is performed by sequentially transferring M, C, and K (black) images. During this transfer, reverse transfer from paper to the drum occurs, albeit slightly. As an example, the transfer of M will be described. When the M image is transferred from the drum to the paper, the Y image is already formed on the paper. The drum on which the M image is formed comes into contact therewith and transfers the M image onto the Y image on paper. At this time, the Y toner on the paper adheres to the M image on the drum. The Y toner adhered to the M drum is cleaned, but a few% of the Y toner enters the developing device when the developing device next develops an image on the drum as a residual cleaning. That is, M in the M developing device
The Y toner is mixed with the toner. In addition, the toner scattered inside the machine and the toner attached to the belt that conveys the paper are mixed into the toners of the developing units of all colors. Therefore,
In a conventional sensor having no spectral characteristic, it is impossible to determine whether the density of a patch has changed or the toner density of the color has really changed because other colors are mixed.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a sensor having spectral characteristics to not only detect a change in toner density but also to detect a color mixing ratio (degree). This makes it possible to perform correction according to the color mixture.

Further, the conventional sensor has the following disadvantages. As the toner is used, since the toner gradually adheres to the inner wall of the glass tube, the transmitted light amount is attenuated by the adhered toner, so that the toner concentration is detected to be higher than the ratio of the true toner in the developer, and as a result, Concentration controls were sometimes lower than appropriate. As a countermeasure, it is conceivable that a service person frequently cleans the inner wall of the glass tube.However, since the glass tube needs to be removed, there is a risk of breakage, and frequent work is very troublesome. Was.

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention corrects a value when a developer is measured with a value when a glass tube is filled with air, so that the value adhered to the inner wall of the glass tube. The effect of the decrease in the amount of light due to the toner is removed, and the toner concentration can be accurately measured over a long period of time without frequent cleaning by a service person.

[0010]

According to a first aspect of the present invention, there is provided an apparatus for irradiating a liquid with a light emitting unit and detecting a liquid concentration based on a change in the amount of reflected or transmitted light from the liquid incident on a light receiving unit. The light emitting means is configured by a light emitting element that emits all wavelengths in the visible light range, and the light receiving means is configured by a light receiving element having a spectral characteristic so as to selectively receive three primary colors of light. It is a characteristic.

According to a second aspect of the present invention, there is provided an apparatus for irradiating a liquid with a light emitting unit and detecting a liquid concentration based on a change in the amount of reflected or transmitted light from the liquid incident on the light receiving unit.
The light emitting means comprises a light emitting element which selectively emits three primary colors of light, and the light receiving means comprises a light receiving element having sensitivity in the entire visible light region.

According to a third aspect of the present invention, in the first aspect, there is provided means for creating a state without liquid (air), and the amount of reflected or transmitted light when there is no liquid is measured, and the measurement is performed based on the measured value. The liquid concentration is corrected.

According to a fourth aspect of the present invention, in the second aspect, there is provided means for creating a liquid-free state (air), and the amount of reflected or transmitted light when there is no liquid is measured, and the measurement is performed based on the measured value. The liquid concentration is corrected.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The left side of FIG. 1 is a part of a developing device,
In the drawing, only the portion containing the developing solution is cut out, and in the figure, 1 is a developing solution, 2 is a pipe for circulating the developing solution or air, and 3 is a solution for switching the passing or stopping of the developing solution. It is a valve. Reference numeral 4 denotes an air valve which allows air to pass therethrough and stops or switches the air. Reference numeral 5 denotes a pump for feeding a developing solution or air into a glass tube 6 for measurement.

FIG. 1 is a block diagram showing one embodiment of a developer density sensor according to the present invention. In the figure, reference numeral 10 denotes a color density sensor, and the color density sensor 10 comprises an illumination lamp 11 and a filter 12 (12B, 12B, 12B, 12B). 12G, 12R) and three phototransistors 13 (13B, 13G, 13R).
Illuminated by the phototransistor 1
By detecting at 3, the concentration of the developer in the tube 6 is optically read. Three phototransistors 13
B, 13G, and 13R receive the transmitted light that is inversely proportional to the developer concentration, and apply a current that is proportional to the amount of light to the resistor 14 (1).
4B, 14G, and 14R), and changes in output current of each of the three phototransistors 13B, 13G, and 13R are converted into voltage changes. 15 (15B, 15G,
15R) is a voltage amplifier, which is a phototransistor 13B,
A weak current change from 13G, 13R is amplified to a sufficiently large voltage change. Reference numeral 20 denotes a main body control unit. The main body control unit 20 includes a microcomputer 22 having an A / D input terminal 21.
The output signals of the voltage amplifiers 15B, 15G, 15R are input to the A / D input terminal 21 of the microcomputer 22.

FIG. 2 shows the illumination lamp 11 to the phototransistor 13 shown in FIG. In this example, the color density sensor 10 includes three LEDs 1 emitting three primary colors of light of B, G, and R, respectively.
1B, 11G, 11R and one phototransistor 13
, And L of only one color selectively lit.
The concentration of the developer 1 in the transparent tube 6 illuminated by ED is read optically. The phototransistor 13 receives the transmitted light inversely proportional to the developer concentration, outputs a current proportional to the amount of light to the resistor 14, and converts a change in the output current of the phototransistor 13 into a change in voltage by the resistor 14. . The weak current change from the phototransistor 13 is amplified by the voltage amplifier 15 into a sufficiently large voltage change. 20 is a main body control section, and the main body control section
As in the embodiment shown in FIG. 1, a microcomputer 22 having an A / D input terminal 21 is mounted, and an output signal of the voltage amplifier 15 is input to the A / D input terminal 21 of the microcomputer 22.

The light emitted from the illumination lamp 11 or the light emitting diodes 11B, 11G, 11R in FIGS. 1 and 2 passes through the glass tube 6, and the phototransistors 13B, 13B.
G, 13R or 13, the light amount Ai is the light amount incident on the glass tube from the light emitting diode: A ₀ The transmittance of the glass: α The transmittance of the toner attached portion: β The transmittance of the developer: γ Assuming that the amount of received light is Ai, it is represented by Ai = α × β × γ × A ₀ .

First, the measurement (reading) of the initial state will be described with reference to the flowchart of FIG. First, in FIG. 1 or FIG. 2, an H signal is output to the output port 23 of the microcomputer 22 in a state where the developing solution does not pass through the glass tube 6, and the transistor array 25 or 25B, 25G, 25
R is turned on, and the illumination lamp 11 or the light emitting diode 11
B, 11G, and 11R are turned on (S1). 16,16
B, 16G and 16R are variable resistors for adjusting the current flowing through the light emitting diode to an appropriate value.
G and 17R are fixed resistors which limit the value of the variable resistor to a minimum value so that the current flowing through the illumination lamp or the light emitting diode does not exceed the maximum rating.

In this case, since the developing solution has not passed, there is no toner adhesion and no developing solution. Therefore, the equation is: A ₂ = α × 1 × 1 × A ₀ = α × A ₀ (influence of only the glass tube 6). At this time, the phototransistor 13 generates a current proportional to the amount of received light, and a voltage proportional to the current is generated across the resistor 14. The voltage is input to the amplifier 15, and a voltage obtained by multiplying the voltage by the amplification is input to the microcomputer 22.
/ D input terminal 21. That is, a signal proportional to the amount of light received by the phototransistor 13 is transmitted to the microcomputer 22.
(S2).

Next, the liquid valve 3 is opened (S3), the air valve 4 is closed (S4), and the pump 5 is turned (S5) to suck up the developing solution 1 and at least reach the upper surface of the glass tube 6. Is satisfied (S6), and the pump 5 is stopped (S7).
Although it is not always necessary to stop the pump 5, by stopping the pump 5, the influence of the flow of minute bubbles is removed, and accurate measurement can be performed. In this state, the amount of light received by the phototransistor 13 is measured in the same manner as described above. First, since it is a new state, no toner adheres to the glass tube 6, and therefore, the equation is A ₃ = α × 1 × γn × A ₀ = α × γn × A ₀ where α × A ₀ = A ₂ , A ₃ = γn × A ₂ (influence of glass tube and new developer). From this, γn = A ₃ / A ₂ ... (S8).

Next, the measurement of the liquid concentration will be described with reference to the flowchart of FIG. Consider the case where toner adhesion 7 occurs on a glass tube after being used for a long time. First, the illumination lamp 11 or the generation diodes 11B, 11G, 11R are turned on (S11), the liquid valve 3 is closed (S12), the air valve 4 is opened (S13), and the pump 5 is turned (S14).
Inhale air. At this moment, the glass tube 6 is wet with the developer 1. For this reason, since it is desired to measure the amount of transmitted light without the developing solution, the pump 5 waits for a time sufficient for the developing solution 1 to flow down from the wall of the glass tube 6 (S15).
Is stopped (S16). Since this time varies depending on the viscosity of the developer to be measured, it needs to be confirmed in advance by an experiment.

It is desirable that the glass tube 6 be used upright to make it easier for the developer to flow down. In this state, the amount of light received by the phototransistor 13 is measured in the same manner as described above (S17). Since there is no developer 1 only with air, the formula is as follows: A ₄ = α × β × 1 × A ₀ = α × β × A ₀ (influence of glass tube and toner contamination). Since α × A ₀ = A _{2 according to the} equation, A ₄ = β × A ₂ β = A ₄ / A ₂ ... Β is the amount of light attenuated due to the occurrence of toner adhesion 7 on the glass tube 6.

In the above description, in order to measure the amount of transmitted light in the absence of the developing solution, the developing solution 1 waited for a time sufficient for the developing solution 1 to flow down from the glass tube 6. performs measurement of the change in received light quantity Te, may the value when the change amount is almost disappeared as a _4.

Next, the air valve 4 is closed (S17), the liquid valve 3 is opened (S18), and the pump 5 is turned (S2).
0) The developer 1 is sucked up, the developer is filled up to at least the upper surface of the glass tube 6 (S22), and the pump 5 is stopped (S22).
23). In this state, the amount of light received by the phototransistor 13 is measured in the same manner as described above (S21). Since toner adhesion 7 occurs on the glass tube 6 and the developer 1 is present, the following expression is obtained: A ₅ = α × β × γ ₀ × A ₀ (Effect of the glass tube, toner stain, and used developer) Become like

[0025] The received light amount A ₅ at this time has received the attenuation due to the toner adhesion 7 of the glass tube 6 may be corrected so as β becomes 1 to determine the amount of light caused by only changes in the concentration of the developing solution 1 That is (S24). That is, A ₆ = α × β × γ ₀ × A ₀ ÷ β = A ₅ ÷ β = A ₅ ÷ (A ₄ / A ₂ ) This value A ₆ assumes that the glass tube 6 has no toner adhesion. Is considered as the amount of light received by the phototransistor 13 at that time. A ₃ = A ₆ if the developer 1 concentration is that the proper, A ₃ <A ₆ Naragenzoeki_1nonodowaususugirutoyuukotodeari,A _3> A ₆ if the developer 1 concentrations conc That is too much.

As described earlier, in the example of the electric circuit of the present invention, the voltage value proportional to the light quantity of the phototransistor 13 can be read from the A / D input terminal 21 of the microcomputer 7, so that the microcomputer 22 is described in the flowchart. As described above, the amount of decrease in the amount of light due to the toner contamination 7 on the glass tube 6 can be corrected, and the change in the developer concentration can be known accurately. In the above description, the switching between the air and the developing solution 1 is performed by switching the two valves. However, one of the valves is immersed in the developing solution, the other is separated from the liquid surface, and the pump is rotated forward, for example. Alternatively, it can be realized by sucking the developer and reversing it to suck the air.
Although the above description has been made on the case of using the transmitted light, the same can be performed by using the reflected light by arranging a light reflecting member on the opposite side of the light emitting element with the developer interposed therebetween.

[0027]

According to the present invention, there is provided an apparatus for monitoring a liquid concentration by irradiating the liquid from a light emitting means and detecting the liquid concentration from a change in the amount of reflected or transmitted light from the liquid incident on the light receiving means. To create a state without air (air)
At this time, the amount of attenuation of the light amount due to toner contamination of the glass tube is obtained based on the amount of the reflected or transmitted light, and the measured liquid concentration is corrected, so that the measurement is accurately performed without being affected by the contamination of the glass tube. The concentration of the liquid can be measured.

[Brief description of the drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of a liquid concentration detection device according to the present invention.

FIG. 2 is a configuration diagram for explaining another embodiment of a liquid concentration detection device.

FIG. 3 is a flowchart showing a measurement procedure in an initial state.

FIG. 4 is a flowchart showing a procedure for measuring a liquid concentration.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Developer, 2 ... Pipe, 3 ... Liquid valve, 4 ... Air valve, 5 ... Pump, 6 ... Measuring tube, 7 ... Adhered toner, 10 ...
Color density sensor, 11, 11B, 11G, 11R ... light source, 12, 12B, 12G, 12R ... filter, 13,
13B, 13G, 13R: Phototransistor, 14,
14B, 14G, 14R: resistor, 15, 15B, 15
G, 15R: Voltage amplifier, 16, 16B, 16G, 16
R: Variable resistor, 17, 17B, 17G, 17R: Fixed resistor, 20: Body control unit, 21: A / D input terminal, 22:
Microcomputer, 23 ... Output port.

Claims (4)

[Claims] 1. A device for irradiating a liquid with a light emitting means and detecting a liquid concentration based on a change in the amount of reflected or transmitted light from the liquid incident on a light receiving means, wherein the light emitting means has a wavelength in all visible light regions. A liquid concentration detection device, comprising: a light-emitting element that emits light; and the light-receiving unit includes a light-receiving element having spectral characteristics so as to selectively receive three primary colors of light. 2. An apparatus for irradiating a liquid with a light emitting means and detecting a liquid concentration from a change in the amount of reflected or transmitted light from the liquid incident on a light receiving means, wherein the light emitting means comprises:
A liquid concentration detecting device comprising a light emitting element for selectively emitting three primary colors of light, wherein the light receiving means comprises a light receiving element having sensitivity in the entire visible light region. 3. The method according to claim 1, further comprising means for creating a liquid-free state (air), measuring the amount of reflected or transmitted light when there is no liquid, and correcting the measured liquid concentration based on the measured value. A liquid concentration detection device characterized by adding: 4. The method according to claim 2, further comprising means for creating a liquid-free state (air), measuring the amount of reflected or transmitted light when there is no liquid, and correcting the measured liquid concentration based on the measured value. A liquid concentration detection device characterized by adding: