JPS6243542A - Developer density measuring apparatus - Google Patents

Abstract

PURPOSE:To achieve a higher measuring accuracy while preventing the lowering of the light transmissivity, by a method wherein a pair of belt-shaped light transmitting members are arranged to face each other in a transferable manner and shifted properly to measure the transmissivity of light passing through a liquid film of a developer. CONSTITUTION:Choking parts 13a and 13b are provided at a concentration measuring section 12 of a developer circulation piping 2 to be linked to a transparent connecting tube 14 while a pair of transparent films 15a and 15b are arranged along the inner side of the connecting tube 14 to face each other in a transferable manner. A liquid film of a developer 1 is formed between the transparent films 15a and 15b while a light emitting element 10 and a light receiving element 11 are arranged to face each other. After a certain service period passes, a driving means is rotated to transfer the transparent films 15a and 15b by a fixed amount as shown by the arrow to place new parts thereof at the measuring section 12. This can prevent the lowering of the light transmissivity caused by impurities attached to the transparent films 15a and 15b.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for optically measuring the concentration of a developer such as liquid toner used in an electrostatic printing device, etc., and particularly to a device used in a concentration measuring section. The present invention relates to means for preventing early reduction in light transmission of a translucent member.

[Conventional technology]

The liquid toner, or developer, used in electrostatic printing devices is used to develop the electrostatic latent image formed on the recording medium, and its density determines the sharpness and sharpness of the developed image. Background fog, etc., has a significant impact on image quality. However, the toner in the developer is gradually consumed each time development is performed, and the concentration of the developer gradually decreases.

Therefore, in order to maintain the concentration of the developer at a certain level,
It is necessary to timely measure the density and automatically replenish toner before the density drops below a certain level.

The most typical of the developer concentration measuring means currently employed is the optical density detecting means described in, for example, Japanese Patent Publication No. 41-21435. The optical density detection means described in Japanese Patent Publication No. 41-21435 has a developer flowing through a passage formed of a transparent member, a lamp and a light-receiving element installed on both sides of this passage, and
This is a means of measuring the concentration of the developer by detecting the light transmittance of the developer. Note that the light transmittance (intensity of transmitted light/
There is a relationship between T (intensity of incident light) and toner concentration (toner weight ff1 contained in the developer per unit weight) D as shown in the following equation.

-J! ogT■Dlld where K is a constant and d is the optical path length (if the attenuation of light by the transparent member is ignored, it is equal to the thickness of the developer layer). Therefore, the toner concentration can be determined from the light transmittance based on the above formula.

[Problem that the invention seeks to solve]

The conventional developer concentration measuring device described above has the following problems. In other words, when used for a long period of time, impurities such as paper powder and dust mixed in the developer, or toner particles, etc., adhere to the inner surface of the transparent member used in the density measurement section, causing the light transmittance to decrease. decrease. This makes it impossible to accurately measure the developer concentration. Possible means to solve this problem include changing the material of the transparent member to a material that is less likely to attract impurities and toner particles, or cleaning the inner wall of the density measuring section from time to time. However, even if the transparent member is made of a material to which impurities and toner particles do not easily adhere, it is impossible to completely prevent the transparent member from becoming dirty, and there is no way to timely clean the inner wall of the concentration measuring section. There is a problem in that it cannot be executed unless the use of the electrostatic printing apparatus main body is once stopped.

Therefore, until now, there has been no effective means for effectively preventing the rapid decline in light transmission through transparent members, and there has been a strong desire for an improvement.

Therefore, the present invention can reliably prevent a decrease in light transmittance due to contamination of the light-transmitting member used in the density measurement section, and can perform highly accurate density measurement. It is an object of the present invention to provide a developer concentration a-j determining device that can perform concentration measurement operations without any trouble even during operation.

[Means for solving problems]

In order to solve the above problems and achieve the objects, the present invention is characterized by taking the following measures. That is, a passage is provided through which the developer whose concentration is to be determined is 7Ipj, and a pair of passages are provided with a predetermined gap between them to form part of this passage and to form a liquid film of the developer between them. The belt-shaped translucent members are arranged facing each other in a transportable manner. Then, the transmittance of light that passes through the liquid film of the developer via the pair of belt-like translucent members is measured.

Then, the pair of belt-shaped translucent members are transported by the transporting means at an appropriate time.

[Effect]

By timely transporting a pair of belt-shaped translucent members,
A new light-transmitting member is always placed in the concentration measuring section.

FIG. 1 is a conceptual diagram of the present invention. As shown in Figure 1,
A thin tube section 3, which is a concentration measuring section, is formed in a part of the developer circulation pipe 2, which serves as a passage through which the developer 1 whose concentration is to be measured flows. Openings 4a and 4b for quick measurement of light transmission of the developer 1 are provided at two opposing locations of the thin tube portion 3. A pair of belt-shaped translucent members 5a are arranged so as to close the openings 4a and 4b to form a part of the passage, and to form a liquid film of developer between them.

5b are arranged facing each other with a predetermined gap in between.

The pair of belt-shaped translucent members 5a and 5b are transported via transport rollers 6.7 and 8,9. This pair of belt-shaped translucent members 5a,
A light transmittance meter a? consisting of a light-emitting element 10 and a light-receiving element 11 measures the transmittance of light passing through the liquid film of the developer 1 via the light-emitting element 10 and the light-receiving element 11. J means are placed facing each other across the openings 4a and 4b.

In this way, if the pair of belt-shaped translucent members 5a and 5b are transferred by a fixed amount at appropriate times via the transfer rollers 6.7 and 8, 9 as shown by the arrows, the pair of belt-shaped translucent members The portions of the members 5a, 5b that close the openings 4a, 4b are replaced by new portions that are not contaminated.

[Example〕 FIG. 2 is a diagram showing a first embodiment of the present invention.

Note that the same parts as in FIG. 1 are given the same reference numerals and detailed explanations will be omitted. A concentration measuring section 12 is provided in the developer circulation pipe 2, which serves as a passage through which the developer 1 whose concentration is to be measured flows.
is formed. This concentration measuring section 12 includes a narrowing section 13 which narrows down the inner diameter of the first piping section 2a in a tapered shape.
a and the constricted part 13b, which is a tapered narrowed inner diameter of the second disposed part 2b, are connected by a transparent connecting tube 14, and a pair of belt-shaped belts are connected along the inner surface of the transparent connecting tube 14. A first transparent film 15a and a second transparent film 15b, which serve as translucent members, are arranged facing each other so as to be transportable.

In this way, the first transparent film 15a and the second transparent film 15b face each other with a predetermined gap in between, and a liquid film of the developer 1 having a predetermined thickness is formed between them. The first transparent film 15a is introduced into the first piping section 2a from the film supply roller 16, and the first transparent film 15a is introduced into the first piping section 2a from the film supply roller 16.
7, the film is guided through the inner surface of the narrowing section 13a, the inner surface of the transparent connecting tube 14, and the inner surface of the narrowing section 13b, and then led out of the second piping section 2b and wound up by the film winding roller 17. It has become something that can be done. Similarly, the second transparent film 15b is attached to the film supply roller 1.
8 into the first piping section 2a, guided by rollers 8.9 and transferred along the inner surface of the narrowing section 13a, the inner surface of the transparent connecting pipe 14, and the inner surface of the narrowing section 13b. The film is led out of the piping section 2b and is wound up by a film winding roller 19. A light emitting element 10 and a light receiving element 11 are disposed facing each other so as to match the opposing positions of the pair of transparent films 15a and 15b. Thus, the transparent connecting tube 14 and the transparent film 1
The transmittance of light that passes through the liquid film of the concentration measuring section 12 through the liquid film 5a and 15b is measured ApI.

In this embodiment configured in this way, the luminescent cord 1
When a total of a-1 lights are emitted from the transparent connecting tube 14 and the first. Second transparent film 15a
, 15b, and the liquid film present at the center thereof, and enters the light receiving element 11.

As a result, an amount of light is incident on the light receiving element 11 in accordance with the concentration of the liquid film, that is, the developer. Therefore, by extracting a signal corresponding to the amount of light received and performing predetermined calculation processing,
The I4 degree of the developer 1 can be determined from the light transmittance.

After a certain period of use, when the film supply roller 16, film take-up roller 17, film supply roller 18, and film take-up roller 19 are rotationally driven by a driving means (not shown), the transparent films 15a, 15
b is transferred by a certain amount as shown by the arrow, and each new transparent film portion is placed on the iQ meter measurement 12. As a result, the transparent film 15a is interposed in the constant portion 12 with a density of 11?1.

15b changes to one having a predetermined transparency without staining. Therefore, it is possible to reliably prevent the light transmittance from decreasing due to impurities, toner particles, etc. adhering to the transparent film. Therefore, even if the concentration is measured over a long period of time, the light transmittance does not decrease due to staining of the transparent films 15a, 15b, and it is possible to perform stable and accurate concentration measurement over a long period of time.

Note that when all the transparent films wound around the film supply rollers 16 and 18 have been used, the film supply roller 16 and the film take-up roller 17 and the film supply roller 18 and the film take-up roller 19 are replaced with new ones. All you have to do is replace it, and the other parts can continue to be used as they are. - Thus, according to this embodiment, by simply transporting the transparent film one after another, it is possible to reliably prevent the light transmittance from decreasing due to adhesion of impurities, toner particles, etc. to the transparent film. Therefore, even if CIf Jilt determination is performed for a long period of time, there is no decrease in light transmittance due to staining of the transparent films 15a and 15b, and stable and accurate density 4P1 determination can be performed for a long period of time. Moreover, it is a transparent film 15a.

Since it is not necessary to particularly clean the density measurement section 12 to ensure the transparency of the electrostatic printing apparatus 15b, density measurement can be performed in parallel while the main body of the electrostatic printing apparatus is in operation.

Next, a second embodiment of the present invention shown in FIG. 3 will be described. The main difference between this embodiment and the first embodiment is that endless tape-shaped transparent films 25a and 25b are used as the transparent films, and the transparent film 25a is used as the transparent film.
The portions a and 25b that are led out of the density 71-1 fixed area are cleaned by cleaning roller 21 and presser roller 22, respectively.
The cleaning roller 23 and the pressing roller 24 are allowed to pass through the cleaning roller 23 and the pressing roller 24. In FIG. 3, numerals 26, 27 and 28, 29 are guide rollers.

According to this second embodiment, in addition to producing the same effects as the first embodiment, the endless tape-shaped transparent films 25a and 25b are endlessly circulated and used while being cleaned. Transparent film 25a even after long-term use.

There are 111 points that are advantageous in terms of maintenance management and ease of repair since there is no need to replace the 25b.

Note that the present invention is not limited to the above embodiments.

For example, in the above embodiment, a case was shown in which transparent films 15a, 15b and 25a, 25b were used as the belt-like translucent member, but it does not necessarily have to be transparent as long as it has a white translucent property! You may also use moss-colored film. Further, in the above embodiments, the present invention was applied to /ai full determination of a developer for electrostatic printing, but it is also widely applicable to the concentration Al1 constant of a developer used for other purposes. It goes without saying that various other modifications can be made without departing from the gist of the present invention.

〔Effect of the invention〕

The developer concentration AI determining device of the present invention is provided with a passage through which the developer flows, and a predetermined gap is provided so that a part of the passage is formed and a liquid film of the developer is formed between the passages. A pair of belt-shaped translucent members are arranged facing each other so as to be able to be transferred, and the transmittance of light that passes through the liquid film of the developer via the pair of belt-shaped translucent members is calculated as i4P+. So,
The present invention is characterized in that the pair of belt-shaped translucent members are configured to be transported at appropriate times by a transporting means.

Therefore, according to the present invention, a new light-transmitting member is always present in the concentration measurement section simply by transporting the pair of belt-shaped light-transmitting members at a timely manner. As a result, it is possible to reliably prevent a decrease in light transmittance due to contamination of the translucent member used in the density/l-1 constant part, and it is possible to perform highly accurate density 71PJ determination, even when using an electrostatic printing device. It is possible to provide an a-degree measuring device for a developer that can carry out a concentration measuring operation without any trouble even when the main body or the like is in operation.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of the present invention, FIG. 2 is a diagram showing a first embodiment of the invention, and FIG. 3 is a diagram showing a second embodiment of the invention. DESCRIPTION OF SYMBOLS 1...Developer, 2...Piping, 3...Thin tube part, 4a
. 4b...Opening portion, 5a, 5b...Belt-like translucent member, 6-9...Transfer roller, 10...Light emitting element, 1
DESCRIPTION OF SYMBOLS 1... Light receiving element, 12... Concentration measurement part, 13a, 1
3b... Squeezing part, 14... Transparent connecting pipe, 15a
, 15b...Transparent film, 16.18...Film supply roller, 17.19...Film winding roller, 21.23...Cleaning roller, 22.24...
...Press rollers, 25a, 25b...Endless tape-like transparent film, 26-29...Guide rollers.

Claims (1)

[Claims] A passage through which the developer whose concentration is to be measured is passed through, and transferable units that form a part of this passage and are arranged facing each other with a predetermined gap so that a liquid film of the developer is formed between them. a pair of belt-shaped translucent members; a means for measuring the transmittance of light that passes through the liquid film of the developer via the pair of belt-shaped translucent members; What is claimed is: 1. A developer concentration measuring device characterized by comprising means for timely transporting the member.