JPH01302143A - Liquid density detector - Google Patents

Abstract

PURPOSE:To achieve a highly reliable liquid density detection, by arranging a set of detection means to detect a intensity level of light transmitted through a liquid to be measured between light emitting and receiving elements and another set of detection means for inputting an output thereof with no liquid to be measured interposed in addition thereto. CONSTITUTION:One set of detection means 1 comprising a light emitting element L using a lamp and a light receiving element PD using a photodiode are arranged in a developing liquid. Another set of detection means 2 made up of a light emitting element LED using an LED and a light receiving element CdS using a CdS are so arranged that there is no developing liquid interposed between the light emitting element LED and the light receiving element CdS. An output current of the light receiving element PD is amplified with amplifiers AMP1 and AMP2 and a light amplifier comprising resistances R1 and R2, a capacitor C1 and the like and then, inputted into the light emitting element LED to emit light. Then, a detection output voltage is obtained depending on a ratio between a resistance value of the light receiving element CdS receiving light and a half fixed resistance R3.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a liquid concentration detection device, and more particularly to a liquid concentration detection bag that can be applied to control the developer concentration in a wet developing method such as a copying machine. [Prior Art] There is a technique disclosed in Japanese Utility Model Application Publication No. 123962/1983 as a developer concentration detection device. In this disclosed technology, a light-emitting element and a light-receiving element are arranged through a gap, and the light-receiving element detects the intensity of light transmitted through the liquid to be measured between the gap, and the detected intensity is used as information for liquid concentration detection. This relates to a so-called light transmission type concentration detection method. [Problems to be Solved by the Invention] CdS or a photodiode is generally used as a light receiving element. For example, when CdS is used, the sensitivity is low, so it is necessary to make the gap between the light emitting element and the light receiving element small. It has been pointed out that the concentration cannot be detected correctly, resulting in a lack of reliability. On the other hand, when a photodiode is used, it is highly sensitive and there is no need to narrow the gap as described above.On the other hand, as shown in Figure 10, the detection output voltage is inversely proportional to the concentration index. It is accompanied by harmful effects due to the appearance of In other words, if we look at the detected output voltage of the vertical axis, which is generated by amplifying the photodiode output with an amplification means, it will quickly become saturated if the developer concentration deviates from the arbitrary set concentration. The current developer concentration cannot be determined. In this case, even if you try to change the set concentration by changing the circuit constant using a semi-fixed resistor, etc., in order to cope with the greatly changing detected output voltage,
This requires significant changes in detection genealogy elements, and as a result, it cannot be performed stably. Therefore, an object of the present invention is to provide a concentration detection means that detects concentration by providing a set of detection means including one light emitting element and receiver and 31 elements in the liquid, and to detect the concentration of the liquid with high reliability. The purpose of the present invention is to provide a liquid concentration detection device that can detect liquid concentration.

[Means to solve the problem]

In order to achieve the above object, in the liquid concentration detection device of the present invention, a light emitting element and a light receiving element are arranged through a gap, and the intensity of light transmitted through the liquid to be measured between the gaps is transmitted to the light receiving element. Detect. In the light-transmission type liquid concentration detection device used for liquid concentration measurement information, there is another device arranged so that the light from the light-emitting element reaches the light-receiving element without passing through the HI+I constant liquid. We decided to provide a set of light emitting elements and light receiving elements. In this case, when a pair of light emitting elements and a light receiving element are used as a set of detection means, one set of detection means provided in the liquid to be measured and one set of detection means provided in a pond outside the liquid to be measured. It is preferable that the relationship between the amount of transmitted light and the received light output in at least one of the sets of detection means be in a non-linear relationship. Furthermore, when a pair of light-emitting element and light-receiving element constitute a set of detection means, the output of the light-receiving element of the set of detection means provided in the liquid to be measured is amplified by an optical amplifier, and It is effective to input the light receiving element of a set of detection means. [Function] In addition to the detection means that detects the intensity of the transmitted light of the liquid to be measured between the gap between the light emitting element and the light receiving element, the output thereof is input,
Another set of detection means in which the liquid to be measured does not exist between the gaps is provided, and the characteristics of the former detection means do not directly control the detected information. The output of the latter detection means becomes detection information. For each set of detection means, the relationship between the amount of transmitted light and the received light output is non-linear.Furthermore, the output of the former detection means is amplified and input to the latter detection means. [Example] The first example describes the electric circuit of the liquid concentration detection device according to the present invention.
In the figure, a set of detection means 1 consisting of a light-emitting element by a lamp and a light-receiving element PD by a photodiode is placed in a developer. Further, another set of detection means 2 consisting of a light emitting element LED made of an LED and a light receiving element CdS made of CdS is configured such that no developer exists at least between the light emitting element LED and the light receiving element CdS. The output type of the photodetector PD is the amplifier AMPI, AMP2.
After being amplified by an optical amplifier consisting of a resistor R2, a capacitor 01, etc., the light is input to a light emitting element LED to cause it to emit light. Then, the detection output voltage is obtained by the ratio of the resistance value of the light receiving element CdS that received this light and the semi-fixed resistor R3. Note that here, the capacitor C1 is for removing noise contained in the output current of the light receiving element PD. Now, the above detected output voltage passes through the A/D converter 3
If the voltage is read by the PU 4 and higher than a preset reference voltage, it is determined that the developer is thin, and the toner replenishment solenoid 5 is driven to perform control to replenish the developer with toner. According to the flowchart in Fig. 2, after copying is performed in step FD, the concentration of the developer is determined by the CPU in step (:: reads the digitally converted detection result, step ]), and the code is determined. Then, in step (3), the toner replenishment solenoid is turned on for a certain period of time to replenish toner. FIG. 3 shows the configuration of FIG. 1 more practically. In the same figure, the detection means l is set to G! The light-emitting element and the light-receiving element PD are attached to a U-shaped bracket 10, and the gap between the light-emitting element and the light-receiving element can be adjusted by turning a gap adjustment screw 15 provided between the arm parts 1'Ob and 10c. G can be :Ua. Bracket 10 is attached to plate 11. By adjusting this gap G, the concentration detection level is initially set. A printed circuit board 13 is provided on the plate 11 with a spacer 12 interposed therebetween, and is equipped with various electric circuit sections including an optical amplifier. On the printed circuit board 13, a semi-fixed resistor R3, a detection means 2,
The connector 14 and the like protrude. The detailed structure of the detection means 2 is shown in FIG. 4, for example. That is, the light-emitting element LE[) and the light-receiving element CdS are integrally fixed in the body 15 made of opaque resin, and the space between the five light-emitting elements LED and the light-receiving element CdS is filled with transparent eA resin. Reference numerals 16 and 17 indicate lead wires 6. Note that instead of the transparent resin, a substance whose transmittance is sufficiently higher than that of the liquid to be measured and is stable may be filled in the gap between the light emitting element LED and the light receiving element CdS. For example, air, silicone oil, chlorofluorocarbon gas, glass, etc. are sealed. Furthermore, the mounting means for each element can be similar to the example of the detection means 1 shown in the third country. In this example, a lamp is used as the light-emitting element in the developing solution, which is the liquid to be measured, and a high-density photodiode is used as the light-receiving element PD to widen the gap, so there is no problem of objects clogging between the gaps, and the output is amplified by an optical amplifier, a light emitting element LED outside the liquid to be measured is made to shine, and the light is received by a light receiving element CdS, so that the relationship between the concentration and the output voltage becomes approximately linear. Therefore, it is possible to widen the gap of the in-liquid detection means to prevent clogging of impurities and to detect concentration over a wide range. The set concentration can also be easily adjusted using a semi-fixed resistor. In other words, ■As the concentration increases, the amount of change in the output current of the light-receiving element PD (output light amount of the light-emitting element LED) decreases (see Figure 5); and ■As the amount of light input to the light-receiving element CdS increases, the resistance changes. The amount of change decreases (see Figure 6), and (1) the detected output voltage is obtained by the ratio of the resistance value of the light receiving element CdS to the resistor R3, so that as the resistance value of the light receiving element CdS increases, the amount of change in the detected output voltage becomes smaller. (See FIG. 7), the concentration versus detection output voltage characteristic can be made into a substantially straight line as shown in FIG. To explain this in more detail, the concentration vs. P shown in FIG.
By combining the D output current (LED output light amount is also the same) characteristic curve and the characteristic curve shown in FIG. 6 above, the characteristic curve shown in FIG. By combining the curve and the characteristic curve shown in FIG. 7, a characteristic showing a substantially linear change as shown in FIG. 8 is obtained. The detected output voltage in FIG. 8 is the input to the A/D converter 3. Therefore, even though a photodiode is used as a light-receiving element in the liquid, the characteristics shown in Figure 10 are ultimately corrected, and even if the developer concentration deviates, it will not become saturated and become undetectable. . If the entire combination of the liquid concentration detection device and the toner replenishment device is used as a control device, the detection means in the conventional control device shown in FIG. 12 includes common parts with the present example,
Since the configuration is such that another detection means is added, there is an advantage that the conventional device can be easily modified to form the present example. This example describes a conventional liquid concentration detection device using CdS as a light receiving element as shown in FIG.
A photodiode is placed in the liquid, and transmitted light corresponding to the liquid concentration, which decreases due to the widening of the gap distance, is transmitted from the photodiosite, which is an in-liquid light receiving element, to L['D, which is an external light emitting element.
The light is amplified by the optical amplification circuit up to the point where it is converted into a large amount of light and input into the CdS, which is an extra-liquid light receiving element. In addition to improving the conventional detection means using CdS, an optical amplifier is added to widen the gap of the in-liquid detection means to avoid clogging of fibers or the like in the gap. FIG. 12 shows a state in which the third rxi liquid concentration detection device is applied to a wet type electrophotographic copying machine. In the figure, during copying, a photosensitive drum 100 is rotated at a constant speed in the direction of the arrow (time rotation) by a drive device, and after being uniformly charged by a main charger 110, an original document a1M is projected by an exposure device. An electrostatic latent image is formed on the photoreceptor drum 100, and the eraser 120
The area outside the image forming area is neutralized. The electrostatic latent image on the photosensitive drum 100 is a wet developing bag to which the present invention is applied! ! ! 1
30 and is transferred by a transfer charger 150 onto a transfer paper S fed from a paper feeding device (not shown) via a conveyance roller 140 as indicated by a broken line arrow. This transfer paper S is separated from the photoreceptor drum 100 by a single-layer roller 160 and conveyed by a conveyor belt 170, and then the toner is fixed by a fixing device and then discharged to the outside. After the transfer paper S is separated from the photosensitive drum 100, residual toner is removed by a cleaning unit 180, and residual potential is removed by a static eliminating lamp 190 (static eliminating device or static eliminating charger), so that the photosensitive drum 100 is prepared for the next copying. The above is an overview of each copying mechanism and process. Next, the wet developing bag [130] will be explained. In the wet developing bag [130], the first. There is a second developer roller and a squeeze roller. The developer is collected into a tank 220 through a collection pipe 210 opened at the bottom of the developer container 1300. The developer is supplied to the liquid supply nozzle 200 through the supply pipe 23 by the action of the pump P installed in the tank 220.
This is done via 0. A developer is supplied from the liquid supply nozzle 200 to a portion of the roller, and the latent image on the photoreceptor drum 100 is visualized. The plate 11 shown in FIG. 3 is installed on the upper plate 220a of the tank 220. The detection means 1 is located in the tank 220, and is set so that the light emitting element and the light receiving element PD are always immersed in the developer. Then, the developer is supplied by the pump P to the gap between the light emitting element rD and the light receiving element rD. [Effects of the Invention] Since the present invention is configured as described above, it produces the effects described below. It is possible to widen the gap in the liquid (another set of detection means that can be used) prevents impurities from clogging between the gaps, and the output characteristics of such a detection means in the liquid are limited to concentration judgments within a narrow range. Even if it is not possible, by combining it with the unique output characteristics of the pond detection means, it is possible to judge the concentration over a wide range, and the reliability of the detection can be improved.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram explaining one embodiment of the present invention, and FIG.
Figure 3 is a flowchart explaining the concentration control process.
The figure is a front view illustrating the arrangement relationship of two sets of detection means according to the present invention, and FIG. Fifth
Figures to 1 (Figure 1 is an output characteristic diagram of a light receiving element, Figure 11 is an electric circuit diagram of a concentration detection device, etc. according to the prior art, and Figure 12 is a configuration diagram of a wet type electrophotographic copying machine to which the present invention is applied). Yes. L, LED... Light emitting element, PD, CdS... Light receiving element 6 Bleeding? ■ Procedural amendment (voluntary) July 1, 1985!; Mouth 1, Incident indication Patent order of 1988 No. 133232 2, Name of the invention Liquid concentration detection device 3, Relationship with the amended case Patent applicant name (674) Ricoh Co., Ltd. 4, Agent Address 4-5-4 Kyodo, Setagaya-ku, Tokyo 5. Column 6 of "Claims" and "Detailed Description of the Invention" of the specification to be amended, contents of the amendment (1) The scope of claims is amended as shown in the attached sheet. (2) Specification No. 5 The text from the beginning of the third line of the page to the end of the seventh line of the same page is changed to the following sentence. It is also effective to amplify the intensity of the light with the optical amplifier, and to arrange it so that the light from the output section of the optical amplifier reaches the light receiving element without passing through the liquid to be measured.'' (3) Change “light” in line 9 of page 6 of the same year to “RFFI style”. (4) Change “here,” in line 13 of page 6 of same year to the following sentence. [Here, the above A configuration in which a light receiving element PD and a light emitting element LED are added to a current amplifier is called an optical amplifier.
(5) Delete "Includes optical amplifier" in the fifth line from the bottom of page 7. (6) Change "light" in the fourth line from just below No. 8 to "current." Attachment Claim 1: A light emitting element and a light receiving element are arranged through a gap,
In a light transmission type liquid concentration detection device in which the light receiving element detects the intensity of light transmitted through the liquid to be measured between the gaps and is used as information for liquid concentration detection. A liquid concentration detection device comprising another set of light emitting element and light receiving element arranged so that light from the light emitting element reaches the light receiving element without passing through the liquid to be measured. 2. When a pair of light emitting element and light receiving element constitute a set of detection means, one set of detection means provided in the liquid to be measured and another set of detection means provided outside the liquid to be measured. 2. The liquid concentration detection device according to claim 1, wherein the relationship between the amount of transmitted light and the received light output in at least one of the sets of detection means is a non-linear relationship. The main 0 light emitting element and the input section of an optical amplifier are arranged through a gap, and the intensity of the light transmitted through the liquid to be measured between this gap is amplified by the optical amplifier, and then the light is arranged at the output section of the optical amplifier. Detected by a light receiving element. A light transmission type liquid concentration detection device used for information for liquid concentration detection.

Claims (1)

[Claims] 1. A light emitting element and a light receiving element are disposed through a gap,
In a light transmission type liquid concentration detection device in which the light receiving element detects the strength of the light transmitted through the liquid to be measured between this gap and is used as information for liquid concentration detection, the light from the light emitting element is detected by the light emitting element. A liquid concentration detection device characterized by comprising another set of a light emitting element and a light receiving element arranged so that the liquid reaches the light receiving element without passing through the liquid. 2. When a pair of light emitting element and light receiving element constitute a set of detection means, one set of detection means provided in the liquid to be measured and another set of detection means provided outside the liquid to be measured. 2. The liquid concentration detection device according to claim 1, wherein the relationship between the amount of transmitted light and the received light output in at least one of the sets of detection means is a non-linear relationship. 3. When a pair of light-emitting element and light-receiving element are used as a set of detection means, the output of the light-receiving element of the set of detection means provided in the liquid to be measured is amplified by an optical amplifier, and 2. The liquid concentration detecting device according to claim 1, wherein the light receiving element of the other set of detecting means is inputted.