JPH05332926A - Detecting apparatus of concentration of liquid - Google Patents

Abstract

PURPOSE:To improve the safety and the reliability of an apparatus by not burying the apparatus in a developing solution thereby to obtain a highly accurate detecting value of the concentration. CONSTITUTION:The apparatus is provided with a concentration measuring roller 601, a Mylar 602 for regulating the amount of a developing solution adhering to the roller 601, a lamp 604 and a photodetecting element 605. The roller 601 has the surface formed of a body which reflects light, greatly. The lamp 604 casts light, to the developing solution on the roller 601 after regulated by the Mylar 602 outside a storing part of the developing solution, and detects the concentration of the solution from the transmittance of light obtained from the reflecting light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copier for wet development,
More specifically, the present invention relates to a liquid concentration detecting device used in an image forming apparatus such as a printer or a facsimile machine. More specifically, a developing solution thinning means is provided near the upper surface of the developing solution, and the developing solution formed by the developing solution thinning means. The present invention relates to a liquid concentration detection device that optically detects the concentration of a thin layer.

[0002]

2. Description of the Related Art Conventionally, in the case of detecting the concentration of a developing solution in a wet copying machine or the like, a light transmission type concentration sensor using a light emitting element and a light receiving element is buried in the developing solution to provide a space between the light emitting element and the light receiving element. This is done by transmitting light to the developing solution. An example of such a concentration detecting device is SAIKAI Sho 61-1.
There is a "developer concentration detector" disclosed in Japanese Patent No. 23962.

In addition to the above examples, as reference technical documents related to the present invention, "Developer concentration detecting device" disclosed in Japanese Patent Laid-Open No. 2-116877 and Japanese Patent Laid-Open No. 2-293.
There is a "liquid concentration detection device" disclosed in Japanese Patent No. 648. This is because a disc-shaped holding member is provided with an opening hole, and a liquid film due to the surface tension of the developer is formed and held in the opening hole.
The light transmittance of the liquid film is detected.

[0004]

However, in the conventional developer concentration detecting device as described above, the light emitting element and the light receiving element are buried in the developer so as to face each other, and the light emitting element and the light receiving element are buried between the two elements. Although the light transmittance of the intervening developer is detected, when a lamp is used as the light emitting element, the filament temperature when the lamp is turned on is as high as 600 ° C. or higher. Therefore, while the lamp is on, the glass of the lamp may be damaged for some reason and the filament may be exposed to the developer. In this case, since the filament temperature exceeds the flash point 340 ° C. of Isopar (petroleum-based organic solvent) that constitutes the developing solution, there is a problem in terms of safety that a fire occurs.

Further, in the above-described concentration detecting device, since the light emitting element and the light receiving element are buried in the developing solution so as to face each other with a gap of about 0.3 to 0.7 mm, dust is trapped between the gaps. As a result, the coarse toner and the like are clogged, and as a result, the concentration sensor cannot accurately detect the developer concentration, and there is a problem in terms of detection accuracy.

Further, "Developer concentration detecting device" disclosed in Japanese Patent Laid-Open No. 2-116877, and Japanese Patent Laid-Open No. 2-116877
In the "liquid concentration detection device" disclosed in Japanese Patent No. 293648, it is difficult to accurately form the thickness of the developer film, and the liquid accumulates between the elements and adhered toner or the like adheres. Therefore, there was a problem in terms of detection accuracy because the variation in the detected value of the developer concentration became large and the developer concentration could not be detected accurately.

The present invention has been made in view of the above, and it is an object of the present invention to improve safety and reliability without burying in a developing solution and obtaining a highly accurate concentration detection value. To aim.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has a surface composed of a high-light reflector and a detection means for adhering a developing solution, and a developing solution adhering to the detection means. The liquid obtained by irradiating the liquid thinning means for controlling the amount of the liquid and the developing solution on the detected means after the liquid thinning means is regulated by the light outside the developer storing portion, and the light obtained from the reflected light. The present invention provides a liquid concentration detecting device comprising a light detecting means for detecting the liquid concentration based on the transmittance.

Further, it is preferable that the detected means has a rotatable cylindrical shape, and the liquid thinning means is constituted by a thin plate material which is in contact with the surface of the detected means.

Further, it is preferable that the detection means has a rotatable cylindrical shape, and the thinning means is a squeeze roller (squeeze roller) arranged at a predetermined interval with respect to the detection means. ..

Further, it is desirable that the rotation speed of the detected means can be variably controlled.

Further, it is desirable that the rotation speed of the squeeze roller can be variably controlled.

[0013]

In the liquid concentration detecting device according to the present invention, the developing solution is adhered to the surface by the detecting means whose surface is made of a high light reflector, and the amount of the developing solution adhered to the detecting means is regulated by the liquid thinning means. To do. After that, the regulated developing solution is made to transmit light, and the liquid concentration is detected by the light transmittance obtained from the reflected light.

[0014]

【Example】

[Embodiment 1] An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing a schematic configuration of a wet type copying machine using a liquid concentration detecting device according to the present invention. In the figure, 101 is a contact glass on which an original to be copied is placed, 102 is an illuminating device for illuminating the original, 1
Reference numeral 03 denotes a scanning mirror for guiding the reflected light obtained by the illuminating device 102, and 104 denotes the reflected light for the photosensitive drum 201 (see FIG. 2).
Lens 105 for forming an image on the recording paper after transfer processing, a fixing device for fixing the image information on the recording paper after the transfer processing, a developing solution tank 106 for storing a developing solution having an appropriate concentration, and a high-concentration developing solution (hereinafter referred to as toner) 107. ) Containing a toner container, 10
8 is a mother liquor container containing a developer such as a petroleum-based organic solvent, 1
Reference numeral 09 is an image forming unit, and 110 is a paper feeding unit that accommodates recording paper and can perform a paper feeding operation based on a paper feeding command. The developing tank 106 is configured to be installed upside down on the upper lid so that the outlets of the toner container 107 and the mother liquor container 108 are on the lower side.

FIG. 2 is an explanatory diagram showing the structure of the image forming unit according to the present invention. In the figure, 201 is a photosensitive drum that forms an electrostatic latent image, 202 is a charger that uniformly charges the surface of the photosensitive drum 201, 203 is an eraser that erases charges outside the image area on the photosensitive drum 201, A developing device 204 is mainly composed of a first developing roller 205, a second developing roller 206, a squeeze roller 207, and the like. Further, 208 is a transfer charger for transferring the image formed on the surface of the photosensitive drum 201 to the recording paper surface, 209 is mainly a cleaning foam roller 210,
The cleaning device includes a cleaning blade 211, a liquid supply hole 212, a liquid diffusion plate 213, a diaphragm roller 214, a liquid recovery hole 215, a recovery pipe 216, and the like.

The first developing roller 2 of the developing device 204
05 and the second developing roller 206 are arranged at a minute interval of 0.1 to 0.2 mm with respect to the surface of the photosensitive drum 201. Further, the squeeze roller 207 is connected to the photosensitive drum 201.
It is arranged with a minute gap of 0.05 mm from the surface. Further, 217 is a registration roller that conveys the recording paper conveyed from the paper feed unit 110 in synchronization with the image on the photosensitive drum 201, and 218 is a separation roller that separates and conveys the recording paper from the surface of the photosensitive drum 201. is there.

In the developer tank 106, a pump 219 which is disposed so as to be submerged in the developer, has a blade for generating a stirring flow of the developer, and rotates, and a concentration sensor 220 for detecting the concentration of the developer. Is provided. 221 is the pump 2
It is a pump drive motor for driving 19. Also, 22
Reference numeral 2 denotes a developing solution supply pipe for supplying the developing solution to the developing device 204, 223 denotes a developing solution supply pipe for supplying the developing solution to the cleaning device 209, and the pump 2
The developer is connected to each device by 19 so that the developer can be supplied.
Reference numeral 224 is a charge eliminating lamp that executes a charge eliminating process by irradiating the photosensitive drum 201 with light.

The operation of the wet copying machine configured as shown in FIGS. 1 and 2 will be described. Contact glass 1
The document on 01 is irradiated by the illumination device 102, and the reflected light is irradiated on the surface of the photosensitive drum 201 via the scanning mirror 103 and the lens 104. On the other hand, the charging charger 202 has already been charged.
Since it has been charged by the photosensitive drum 201,
An electrostatic latent image is formed on the surface according to the irradiation light. The developing device 204 develops (attaches) the developing solution to the electrostatic latent image by the first developing roller 205 and the second developing roller 206 to make it a visible image.

Subsequently, the recording paper is conveyed from the paper feed unit 110 to the registration roller 217, and the registration roller 217 sends the recording paper to the transfer unit in time with the image formed on the photosensitive drum 201. The image on the surface of the photosensitive drum 201 is transferred onto the recording paper by the action of the transfer charger 208. Next, the recording paper onto which the image has been transferred is separated from the photosensitive drum 201 by the separation roller 218, conveyed to the fixing device 105, where the fixing process is executed, and the recording paper is ejected to the outside of the machine. On the other hand, the residual toner on the photosensitive drum 201 after the transfer process is removed by the cleaning device 209. After that, the photosensitive drum 201 after removing the residual toner
The residual charge on the surface is erased by the discharge lamp 224, and a standby state is set up for the next copying instruction.

Next, the developing device 204 for handling the developing solution,
The developer tank 106, the cleaning device 209 and the like will be described in more detail. The first developing roller 205 and the second developing roller 206 of the developing device 204 are driven by the drive device in the direction of the arrow in the direction opposite to the photosensitive drum 201, and
It is rotationally driven at a peripheral speed higher than that of the photosensitive drum 201. The developing solution is supplied into the developing apparatus 204 by the developing solution supply pipe 222 connected to the upper portion of the developing apparatus 204, and
It is stored between the developing roller 205, the second developing roller 206, and the scraper that contacts the roller. Then, the developing solution is applied to the first developing roller 205 and the second developing roller 2
When the electrostatic latent image on the photosensitive drum 201 is developed by being uniformly conveyed to the surface of the photosensitive drum 201 by the rotation of 06, the collecting pipe 2 provided at the bottom of the developing device 204.
After passing through 16, it is returned to the developing tank 106 as a residual liquid and reused.

The concentration value of the developing solution in the developing tank 106 is detected by a concentration sensor 220, and toner is replenished from the toner container 107 into the developing tank 106 based on a well-known toner replenishment control method using the detection signal. It is stored in the developing tank 106 as a developing solution. The developing solution is supplied by the pump 219 to the developing device 204 and the cleaning device 209 via the developing solution supply pipes 222 and 223. Then, after the developing process and the cleaning process are executed, the developing solution is collected in the developing tank 106 through the collecting pipe 216 and recirculated.

FIG. 3 is a block diagram showing the control system of the wet copying machine according to the present invention. In the figure, a control system is a CPU (microcomputer) 3 that mainly executes arithmetic processing and control based on program data in the ROM 303.
01, RAM30 for storing the calculation result of the CPU301
2, ROM 303 storing program data,
An I / O port buffer 304, an operation unit 305 (305a is a buffer) composed of a key SW group, a display unit 306 composed of a display unit, a detection sensor unit 307 for detecting each state in the apparatus, a PWM (pulse) A pulse oscillator 308 for generating a pulse signal such as a width modulation signal, a driver 309, and the like. Further, 310 is an ADF (automatic document feeder), and 311 is an optical system.

In the above, the operation unit 305 of the wet copying machine is used.
Key input, a detection signal from the detection sensor unit 307, and a pulse signal from the pulse oscillator 308 synchronized with the photosensitive drum 201 are input to the CPU 301 via the buffers 305a. The CPU 301 is connected to the ROM 303, the RAM 302, and the I / O port buffer 304 via an address bus, a data bus, etc., and the I / O port buffer 30
4 is driven via each driver 309, and further the display unit 30
6 shows various states of the apparatus.

Here, the toner replenishing mechanism will be described. FIG. 4 is an explanatory view showing the toner replenishing portion according to the present invention, and the toner replenishing portion is provided on the upper lid portion of the developing tank 106. In the figure, a valve 401 is biased by a spring 402 in the toner container 107, and a shaft portion of the valve 401 projects from an outlet. Further, the tip of the arm 403 is brought into contact with the protruding portion of the valve 401, and the arm 403 is turned on / off by the solenoid 404.
1 is a mechanism that can be moved up and down. In the above configuration, when the developer concentration becomes equal to or lower than the set value by the detection signal from the concentration sensor 220, the solenoid 404 is suction-driven (ON), and the toner container 107 is closed by the biasing force of the spring 402. Is released by pressing the arm 403, and the toner in the toner container 107 is replenished in the developer tank 106.

FIG. 5 is an explanatory view showing the developer replenishing section according to the present invention, in which the mother liquor container 108 is inverted, and the valve 50 urged by the spring 501 is provided at the outlet thereof.
2 is provided, which is a so-called chicken feed valve type mechanism. In the above configuration, the mother liquor container 1
As shown in FIG. 8, when the developer surface in the developer tank 106 is lower than the reference surface 08, the discharge port communicates with the atmosphere and the developer in the mother liquid container 108 flows into the developer tank 106 to be replenished.

Next, the density sensor 220 according to the present invention will be described. 6 to 8 are explanatory views showing the first embodiment of the concentration sensor according to the present invention. In the figure, 60
Reference numeral 1 denotes a density measuring roller made of a material having a high reflection characteristic such as glass, which is configured to be partially embedded in a developing solution and rotatable. Further, a mylar (polyester film) 602 for uniformly thinning the developing solution is brought into contact with the surface of the density measuring roller 601, and a scraper 603 for scraping off the developing solution on the surface of the density measuring roller 601 is applied to the other side. It is touched. Further, a lamp 604 (light emitting element) and a light receiving element 605 are respectively surrounded by a shielding plate 606 as a light transmission measuring section on the upper part of the density measuring roller 601, and the surface of the density measuring roller 601 is irradiated with the light of the lamp 604. It is arranged so that the reflected light enters the light receiving element 605.

FIG. 7 shows the shape of the mylar 602 and its contact state. The tip portion of the mylar 602 is provided with a stepped portion between the portion A for thinning the developing solution and both end portions B thereof, as shown in the figure. Further, the Mylar 602 has a thickness of 0.1 to
Using the one having a size of about 0.6 mm, lightly abutting on the density measuring roller 601, the portion A of the mylar 602 and the density measuring roller 6
01 surface is formed with a predetermined gap. In the above configuration, the density measuring roller 601 is rotated in the illustrated rotation direction, and the developing solution is attached to the surface thereof by the action of surface tension. The attached developer is Mylar 602.
Due to the gap between the portion A and the surface of the density measuring roller 601, a thin developer layer 801 having a uniform thickness is formed as shown in FIG.
The thin developer layer 801 is sent to the light transmission measuring unit.

Next, the light emitted from the lamp 604 is
The light passes through the thin developer layer 801 and reaches the surface of the density measuring roller 601 (transmitted light). At this time, the density measuring roller 60
1 The surface has high reflection characteristics, so the transmitted light is reflected,
The light again passes through the thin developer layer 801 and enters the light receiving element 605. The light receiving element 605 outputs a detection signal according to the received light. The concentration of the developing solution is judged from the detection output from the light receiving element 605, and when the concentration is lower than the set concentration,
The above-mentioned toner supply mechanism, that is, the solenoid 404 is turned on.
Then, the arm 401 operates to open the valve 401 of the toner container 107 to replenish the toner. This is executed until the set density is reached. Then, the thin developer layer 801 is scraped off by the scraper 603 from the surface of the density measuring roller 601. This is so that the next time a new developer adheres to the surface of the density measuring roller 601, it will not be affected by the previously adhered developer.

Second Embodiment Next, FIG. 9 shows a second embodiment of the concentration sensor according to the present invention. In FIG. 9, a squeeze roller (squeezing roller) 901 is arranged so as to be rotatable with respect to the surface of the density measuring roller 601 at a minute interval of 0.05 to 0.5 mm instead of the Mylar 602 in the configuration of the first embodiment. It is set up. Further, a scraper 902 for scraping off the developer is provided in contact with the squeeze roller 901, and the squeeze roller 901 is set in a rotation direction opposite to the density measuring roller 601.
The density measuring roller 601 and the squeeze roller 901 are each an independent drive mechanism (not shown). In the above structure, the developer adhering to the surface of the density measuring roller 601 becomes a thin developer layer 801 by the squeeze roller 901 as shown in FIG. 9, and is sent to the light transmitting portion in the same manner as described above to execute the density detecting process. To be done. Further, the developer attached to the squeeze roller 901 is removed by the scraper 902.

Since the squeeze roller 901 is used as a means for making the thickness of the developing solution thin layer 801 uniform, the thickness of the developing thin layer 801 can be made more uniform and the density detection accuracy can be improved. To improve. Further, in the above description, the gap between the squeeze roller 901 and the density measuring roller 601 is adjusted, and the rotational speed of the squeeze roller 901 is variably adjusted to adjust the density measuring roller 60.
The amount of the developer thin layer 801 attached to one surface can be adjusted.

Next, the rotation control of the density measuring roller 601 and the squeeze roller 901 will be described. Figure 1
Reference numeral 0 is a block diagram showing a drive control circuit of each drive motor according to the present invention.
And the squeeze roller drive motor 1002 is a CPU 301.
It is configured to be controllable by. A / of CPU301
D input 1 (for density measuring roller 601) and A / D input 2
(For squeeze roller 901) each has a variable resistor VR1,
VR2 is connected as the input side. Also, CPU3
01 as the output side of the density measuring roller drive motor 1001
And a PWM output 2 for controlling the squeeze roller drive motor 1002.

Setting of the peripheral speed of the density measuring roller 601 by the drive control circuit configured as described above will be described.
11. FIG. 11 is a graph showing A / D conversion values (converting analog values into digital values) and DUTY values according to the present invention. 10 and 11, when analog amount data is input to the A / D input 1 via the variable resistor VR1, the CPU 301 converts the analog data into digital data between 00H and FFH according to the input of the analog data. .. C
PU301 is the data of A / D input 1 (00H to FFH)
The DUTY value (0 to 100%) corresponding to is calculated. Based on the obtained DUTY value, the PWM output 1 oscillates a pulse signal to TR1. As a result, the density measuring roller drive motor 1001 is rotated at a speed according to the DUTY value.

As described above, the rotation speed of the density measuring roller 601 can be controlled by changing the variable resistance VR1. As a result, the thickness of the thin developer layer 801 can be changed. Similarly, the peripheral speed of the squeeze roller 901 is set based on the setting of the variable resistance VR2. Therefore, the rotation speed of the density measuring roller 601 can be controlled to change the thickness of the thin developer layer 801.
It is also possible to set from the rotation speed of. Also,
Since the thickness of the developer thin layer 801 can be changed by changing the rotation speed of the squeeze roller 901, the developer concentration can be set also from the rotation speed of the squeeze roller 901.

Here, the output adjustment of the density sensor 220 will be described. FIG. 12 is a circuit diagram of the concentration sensor according to the present invention, and FIG. 13 is a graph explaining the output state of the concentration sensor according to the present invention. In FIG. 12, 1201 is a variable resistor used for output adjustment.
Further, the graph shown in FIG. 13 shows the relationship between the output value (v) of the light receiving element 605 and the number of copies processed.

In FIG. 13, when the output of the light receiving element 605 reaches a level corresponding to the upper limit of the concentration setting range (equivalent to the lower limit of the developer concentration), the toner replenishment part ( The drive signal of the solenoid 404 (see FIG. 4) is output, toner supply is started, toner is supplied to the developer tank 106, and the developer concentration increases. As a result, the output of the light receiving element 605 decreases. Thereafter, the output of the light receiving element 605 increases again as the toner is consumed, and when the upper limit level is reached, the toner replenishing operation is executed again. By repeating such an operation, the developer concentration is controlled within the set range.

In this embodiment, after the developer is set to a concentration within a certain range, the concentration changes (becomes thin) when the copying process is started and the developer is used. Since it is necessary for the copying machine to utilize the developer concentration measurement value measured by the density sensor 220 during the copying process and during the standby (copy preparation period), the density sensor 220 outputs Judgment using the detection output is executed during the copying process and during standby. Further, the detection of the developer concentration and the toner replenishment control are executed while the developer is being stirred by the rotation of the pump 219.

Here, "during copying" means, for example, that the last recording sheet (in the case of copying processing of only one sheet, the recording sheet corresponds to the sheet after the operator has pressed a copy start button (not shown)). However, in the case of continuous copy processing, this is the period until the last sheet of recording paper is discharged outside the machine. Also, "standby" means that the main power supply of the device is
After N, the fixing device 105 is heated to a predetermined temperature or the developing solution is circulated to initialize the surface of the photosensitive drum 201, the developing device 204, the cleaning device 209, and the like, during idling, and at the end of the copying process. When it is detected that the developer concentration has dropped below a predetermined value at the time of, the developer concentration control is executed subsequently (after toner is replenished) in preparation for the next copy process.
During the period.

As described above, the density sensor 2 according to this embodiment
Since the lamp 604 and the light receiving element 605 are configured and arranged so as not to be immersed in the developing solution, the light receiving surface of the light receiving element 605 is not contaminated with the developing solution, and the clogging trouble of the conventional concentration sensor with the developing solution is prevented. The detection failure of the density sensor 220 is eliminated.

[0039]

As described above, according to the liquid concentration detecting device of the present invention, the surface is composed of a high light reflector,
For the detection means to which the developing solution is attached, the liquid thinning means for controlling the amount of the developing solution adhering to the detection means, and the developer on the detection means after the regulation by the liquid thinning means And a light detection means for irradiating light outside the developing solution storage portion and detecting the solution concentration by the light transmittance obtained from the reflected light, so that the accuracy is maintained without being embedded in the developing solution. It is possible to improve safety and reliability by obtaining a high concentration detection value.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a wet copying machine using a liquid concentration detecting device according to the present invention.

FIG. 2 is an explanatory diagram showing a configuration of an image forming unit shown in FIG.

FIG. 3 is a block diagram showing a configuration of a control system of the wet copying machine according to the present invention.

FIG. 4 is an explanatory diagram showing a toner replenishing section shown in FIG.

5 is an explanatory diagram showing a developer replenishing section shown in FIG. 1. FIG.

FIG. 6 is an explanatory diagram showing a configuration of a density sensor (Example 1) according to the present invention.

FIG. 7 is an explanatory diagram showing a configuration of a density sensor (Example 1) according to the present invention.

FIG. 8 is an explanatory diagram showing a detection state of the density sensor (Example 1) according to the present invention.

FIG. 9 is an explanatory diagram showing a configuration of a density sensor (Example 2) according to the present invention.

FIG. 10 is a block diagram showing a configuration of a drive control circuit of each drive motor according to the present invention.

FIG. 11 is a graph showing a relationship between an A / D converted value and a DUTY value according to the present invention.

FIG. 12 is a circuit diagram showing a configuration of a concentration sensor according to the present invention.

FIG. 13 is a graph showing an output state of the density sensor according to the present invention.

[Explanation of symbols]

106 developer tank 107 toner container 108 mother liquor container 109 image forming unit 201 photoconductor drum 204 developing device 301 CPU 302 RA
M 303 ROM 305 Operation unit 306 Display unit 307 Detection sensor unit 308 Pulse oscillator 601 Density measuring roller 602 Mylar 604 Lamp 605 Light receiving element 801 Developer thin layer 901 Squeeze roller 902 Scraper 1001 Density measuring roller drive motor 1002 Squeeze roller drive motor

Claims (5)

[Claims] 1. A detection means having a surface made of a high-light reflector for adhering a developing solution, a liquid thinning means for regulating the amount of the developing solution adhering to the detection means, and the liquid thinning. And a photodetector for detecting the liquid concentration based on the light transmittance obtained from the reflected light of the developing solution on the detected means after the regulation by the means. A liquid concentration detection device characterized by the above. 2. The detection means has a rotatable cylindrical shape, and the liquid thinning means is made of a thin plate member that is in contact with the surface of the detection means.
The liquid concentration detection device described. 3. The detection means has a rotatable cylindrical shape, and the thinning means is a squeeze roller (squeeze roller) arranged at a predetermined interval with respect to the detection means. The liquid concentration detecting device according to claim 1. 4. The liquid concentration detecting apparatus according to claim 2, wherein the detected means is capable of variably controlling the rotation speed thereof. 5. The liquid concentration detecting device according to claim 3, wherein the rotation speed of the squeeze roller can be variably controlled.