JPH03200176A - Image forming device - Google Patents

Abstract

PURPOSE:To always form an image with constant developing density without relying on the dependency on the change of humidity by controlling the start of toner replenishment and the stop of the toner replenishment at a voltage corrected according to the humidity. CONSTITUTION:A humidity detection means 5 is provided and the output voltage generated according to the humidity detected by the means 5 is inputted in a control means 4c, so that the start of the toner replenishment and the stop of the toner replenishment are controlled at the voltage of a value obtained by correcting the toner replenishing start voltage and the toner replenishing stop voltage of the set value of the developer in a developing means 1, which are previously stored, according to the humidity. Therefore, even when ambient environment, especially, a humidity condition, are varied and the output voltage generated in a toner concentration detection means 3 is changed, the toner replenishing start voltage and the toner replenishing stop voltage are corrected according to the variation of the concentration and the start of the toner replenishment or the stop of the toner replenishment is performed. Thus, the toner specific concentration of the developer in the developing means is always stable regardless of the change of the humidity and the toner concentration of the formed image is not varied.

Description

[Detailed description of the invention]

[Objective of the Invention] (Industrial Application Field) The present invention relates to an improvement of an image forming apparatus using an electrostatic recording method, and more specifically, to an improvement of an image forming apparatus using an electrostatic recording method, and more specifically, to an improvement of an image forming apparatus using an electrostatic recording method. The present invention relates to an image forming apparatus that can be used. (Prior Art) An image forming apparatus using the static f'fs recording method forms an electrostatic latent image corresponding to the optical image of the original image on a photosensitive image support by charging and exposing it, and then the electrostatic latent image is formed by a developing device. A developer is applied to the latent image to form a visualized L/S image, and the toner image is further transferred and fixed onto a transfer target in a transfer unit to form an image. Conventionally, as shown in FIG. 6, the developing device 1 used at this time has a magnetic brush roll 8 located in a developing casing 6 on the side in contact with a photosensitive image support 7 (not shown). Adjacent to the brush roll 8 and at regular intervals, stirring blades 9 for stirring and mixing the developer are also connected to the magnetic brush roll 8.
A toner concentration detector '3 is disposed on the doctor 1.0.10 at the top of the stirring blade 9, and the stirring blade 9 is rotated (in the direction of the arrow) to agitate the developer contained in the casing 6. As the magnetic brush roll 8 is conveyed to the magnetic brush roll 8 side and rotated, the developer is caused to adhere to the outer peripheral surface of the magnetic brush roller 8 by a magnet member on the outer periphery of the magnetic brush roller 8, thereby forming an electrostatic latent image on the image support 7. ]・The structure is such that the car is attached. On the other hand, an electrostatic recording type image forming apparatus uses [
A two-component developer consisting of toner j and “carrier” (hereinafter simply “
(referred to as "developer") is used. The toner contained in the two-component developer uses colored thermosetting thermoplastic particles, and the carrier uses coarse magnetic carrier particles made of ferromagnetic material such as iron powder. The amount of is at most the number of carriers W

[%, and the rest is carrier. The amount of component toner in the developer is then selected to impart an appropriate charge to the electrostatic latent image formed on the image support 7''. Therefore, when the developer described above is housed in the developer casing 6 and brought into contact with the electrostatic latent image on the image support 7 while rotating the magnetic brush roll 8 while the developer is attached to the magnetic brush roll 8, the electrostatic latent image is L·Car mainly adheres to the forming surface, and most of the carrier remains on the roll 8. Therefore, the developer contained in the developing casing 6 contains toner (T
m becomes smaller, and the toner/carrier weight ratio (rT/
(abbreviated as CJ) decreases each time development is performed, and the amount of toner in the developer, which is originally small, further decreases, making the toner concentration unstable. Therefore, in order to solve this problem, conventionally, a toner cartridge is attached as a lower toner supply stage via a connecting member 23, which will be described later, and the toner concentration of the developer in the developing device is detected (2,
When the component toner in the developer in the developing device becomes low, a method is adopted in which the component toner is replenished from the toner cartridge 22. That is, as shown in FIG. 7, the cartridge connecting part holder 23 is equipped with a slider 25 that opens and closes with two toner cartridges and one latch 28 structure, and the cartridge connecting part holder 23 is also equipped with a slider 25 that opens and closes with a structure of two toner cartridges and one latch 28.
A rotary printer 2 is provided with a slide shutter opening 1126 for toner discharge at 3, and opens and closes the toner discharge port 24.
7. The toner stored in the toner cartridge holder 22 is discharged when the slider and slider openings 26 match, and when they do not match, the toner replenishment is stopped. The opening and closing of the toner cartridge is performed by driving a toner replenisher (not shown), which is controlled in accordance with control signals from a central processing unit (hereinafter abbreviated as JCPUJ) 4, as shown in FIG. This is because the developer in the developing device 1 has the property that the T/C vs. output voltage (, V) characteristic of the toner concentration detector 3 changes as shown in the characteristic curve a in FIG. 8 depending on the toner concentration ratio, and the toner If toner replenishment is started when the output voltage of the density detector 3 becomes higher than toner replenishment start voltage B, and toner replenishment is stopped when the output voltage becomes lower than toner replenishment stop voltage A, the developing device This is based on the idea that the specific toner density of the internal developer is stable and that the toner density of the formed image is constant. (Problem to be Solved by the Invention) However, the developer, that is, the two-component developer, has environmental dependence, and especially when the humidity is around 70%, for example, the T/C becomes (4,Qwt%). In the case of the developer, the output voltage (V) generated in the toner concentration detector 3 is higher (indicated by the arrow) than the characteristic curve a at normal pressure, as shown in the characteristic curve b (broken line) in FIG. For this reason, the CPU determines that the T/C has decreased, and the L/Car concentration detector 3 outputs voltage (A).
Continue to replenish toner until the voltage drops to (However, some types of developer have poor fluidity when humidity increases, so the output voltage may decrease.) For this reason, the T/C of the developer is controlled to be higher (4.0 wt%) than the normal humidity state. The toner in the image forming device becomes excessive, causing toner scattering into the image forming device, and causing "fogging" and stains on the image. Furthermore, since the amount of toner consumed increases, problems such as not being able to reach the specified number of copies may occur. The present invention was made based on the above-mentioned circumstances of the conventional image forming apparatus in which the toner replenishment of the developer in the developing device is controlled by the CPU. It is an object of the present invention to provide an image forming apparatus in which the specific toner density of an internal developer is always kept constant, the reliability is high, and an image with a good development density is formed. [Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, an image forming apparatus of the present invention basically has the structure shown in FIG. That is, a developing means 1 containing a two-component developer, a replenishing means 2 for replenishing the developing means 1 with toner of the developer, and detecting the toner specific concentration of the developer in the developing means 1, and detecting the toner specific concentration. a density detecting means 3 that outputs a voltage according to the density detecting means 3; and a voltage output from the density detecting means 3 is inputted, and the input voltage and the toner replenishment start voltage of the set value of the developer in the developing means] and the toner When the output voltage is larger than the toner replenishment start voltage, the toner replenishment means 2 is controlled to replenish the toner, and when the output voltage is smaller than the toner replenishment stop voltage, A control means 4C (see FIG. 4) for controlling the replenishment means 2 to stop toner replenishment, and a humidity detection means 5 for detecting the humidity of the developing means 1, which is further provided in the image forming apparatus. means 5, inputs the voltage output in response to the humidity detection by the humidity detection means 5 to the first control stage 4a, and sets the toner supply start voltage and toner supply stop voltage of the set values, respectively. This is characterized in that the start or stop of toner replenishment is controlled using a voltage that is the sum of a voltage that increases or decreases in response to changes in humidity. (Function) As described in "2" below, the image forming apparatus is provided with the humidity detection means 5, and the output voltage generated in accordance with the humidity of the humidity detection means 5 is inputted to the control means 4C, and a large amount is stored. In order to control the toner replenishment start voltage and toner replenishment stop using voltages obtained by adding corrections according to humidity to the toner replenishment start voltage and toner replenishment stop voltage of the set value of the developer in the developing means 1, Even if the surrounding environment, especially the humidity condition, changes and the output voltage generated in the density detection means 3 changes, the toner replenishment start voltage and toner replenishment stop 1-voltage are corrected according to the humidity fluctuation, and the toner replenishment start or stop voltage is corrected according to the humidity fluctuation. Since the toner supply is stopped (1-), the specific toner concentration of the developer in the developing device is always stable regardless of changes in humidity, and there is no fluctuation in the toner concentration of the formed image. (Example) Next, an example of the present invention will be described with reference to the drawings. FIG. 2 shows a schematic configuration of an image forming apparatus according to an embodiment of the present invention. In the figure, 11 is a housing of the main body, and a photosensitive drum 1 is provided as a photosensitive image support in the housing 11.
A charger 13, a light beam irradiation system 14, a developing device 1, a transfer unit 15, a cleaning device 16, and a static elimination lamp are arranged around the photosensitive drum 2 along the rotation direction (indicated by an arrow). 17 are provided in sequence. The developing device 1 has the same configuration as the conventional device shown in FIG. In addition, stirring blades 9 are arranged at regular intervals to stir and mix the developer, and a toner concentration detector 3 is arranged on the magnetic brush roll 8 and the doctor 10.10 above the stirring blades 9, and the stirring blades 9 are rotated. At the same time, the developer is conveyed to the magnetic brush roll 8 side, and the developer is deposited on the outer periphery of the magnetic brush roll 8 by the rotation of the magnetic brush roll 8, and the electrostatic charge on the image support [11 body 12] is The structure is such that toner adheres to the latent image. In addition, a paper feed cassette 18 is attached to the lower portion of the Housong 1, and is configured to be able to sequentially pull out the transfer sheets P. Then, the taken-out transfer sheet P passes between aligning rollers 19 and 19, passes through the outer peripheral surface of the photoreceptor drum 2, is conveyed along the rotational direction of the photoreceptor drum 12, and passes through the heating/fixing unit 20. , and are sent out toward the tray 21. Further, a toner cartridge 22 is connected to the developing device 1 for replenishing the component 1. As shown in FIG. 7, the toner cartridge 22 is disposed via a cartridge part 23. Toner in the toner car 1 - ridge 22 is removed by a slide shutter 25 and a rotary shutter 27 that move left and right by a rack-pinion mechanism 29 that meshes with a toner shaft that is rotationally driven by the operation of a drive motor (not shown) in the cartridge connection assembly 23 . is discharged into the developing device l. Further, in the developing device 1, as in the conventional device shown in FIG.
T/C-4 containing 4 wt% component toner in casing 6
Two-component developer is stored therein, and the toner specific concentration of the developer in the developing device 1 is detected by a magnetic auto-toner sensor 3a. The output voltage of the toner specific density detection by the magnetic auto-toner sensor 3a is input to the CPU 4 as shown in FIG.
/C-4 is compared with the toner replenishment start voltage B (see Figure 3) and toner replenishment stop voltage A of the two-component developer setting value (calculation unit 4b), and the input voltage from the magnetic auto-toner sensor 3a is compared. When the value is larger than the set value of toner replenishment voltage, the control device 4c operates a toner cartridge drive motor (not shown) to start replenishing toner to the developing device 1 with the toner cartridge 22, and the magnetic auto toner is activated. When the voltage value input from the sensor 3a becomes smaller than the set value of toner replenishment stop voltage A, toner replenishment to the developing device is stopped (1-). Furthermore, the image forming apparatus of the embodiment is provided with a humidity detection sensor 5a as shown in FIG.
The voltage output according to the humidity change due to a is CPU4
is inputted into the storage device 4a, and added as a correction value to the toner replenishment start voltage B or toner replenishment stop voltage A, which is a set value stored in advance in the storage device, in the arithmetic unit 4b, and the toner replenishment of the added value is started. Control is performed to stop toner replenishment or toner replenishment of the toner cartridge 22 for replenishing toner to the developing device 1 via the control device 4C using the voltage or toner replenishment stop voltage. The developer used in this example was described as having a T/C vs. output voltage characteristic as shown in the characteristic curve a in FIG. 3 in the case of a magnetic autotoner sensor. It is not limited to those that use a developer such as the above, but also those that have a high output voltage under humid conditions F as shown in the characteristic curve in Figure 1. It goes without saying that voltages such as A) in which the output voltage is lower can also be used. In this invention, a humidity detection sensor is installed in the image forming apparatus, and the humidity detection sensor detects the atmospheric humidity and sends the humidity information to the CPU, and the CPU generates toner that corresponds to the humidity change stored in advance according to the output of the sensor. Correct the output voltage level of the concentration detector. For example, in the case of Fig. 3, even if the output voltage increases as shown in characteristic curve a during high humidity, the CPU corrects the toner replenishment voltage to B based on the feedback of the humidity detection sensor, so toner replenishment starts. Not done. When image copying is performed, the T/C decreases and the output voltage increases, and when the output exceeds the toner replenishment voltage B, the CPU determines that the T/C is low and outputs toner? Toner is replenished until the toner supply stop voltage falls to A, and control is performed so that T/C is always 4.0wt%, so toner is not oversupplied (・. Also, when the output voltage is high in high humidity) Even if a developer is used that lowers the toner replenishment voltage, the voltage correction value due to humidity changes is stored in the CPU in advance using feedback from the humidity detection sensor so that the toner replenishment stop voltage and toner replenishment start voltage are A (see Figure 3). 0 (Figure 5). (T/C does not become too low) Also, even when the humidity is low, it is sufficient to store it in the CPU using the same method. The developed developer has a T/C of 4.
．． Qwt% was explained as a representative example, but T/C is 4. The developer is not limited to Qwt%, but may be a two-component developer having a T/C value larger or smaller than this. [Effects of the Invention] As is clear from the above description, the image forming apparatus of the present invention is provided with not only a toner concentration detecting means but also a humidity detecting means, and a pre-stored developing The toner replenishment start voltage and the component toner replenishment stop voltage of the set values of the developer in the means are controlled to start and stop toner replenishment at voltages that are corrected according to the humidity. It is possible to always form images with a constant developing density without being affected by environmental dependence, especially dependence on changes in humidity.Also, even if humidity conditions change, image fogging and toner scattering inside the image forming device are avoided. ) Never falter.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of the basic configuration of an image forming apparatus according to the present invention, FIG. 2 is a cross-sectional explanatory diagram of main parts showing the schematic configuration of an embodiment of the invention, and FIG. 3 is a diagram showing a developing device of the embodiment. A T/C vs. output voltage characteristic diagram of the developer used, FIG. 4 is a schematic block diagram of an image forming apparatus according to an embodiment of the present invention, and FIG. 5 is a detailed block diagram of main parts of the image forming apparatus shown in FIG. 6 is an explanatory cross-sectional view of a main part of a developing device used in a conventional image forming apparatus, FIG. 7 is a cross-sectional view of a main part showing the configuration of a connecting part of a conventional toner cartridge, and FIG. 8 is a cross-sectional view of a main part of a developing device used in a conventional image forming apparatus. FIG. 9 is a characteristic diagram showing the relationship between the T/C of the developer used in the developing device of the forming apparatus and the output voltage, and FIG. 9 is a block diagram of an image forming apparatus using a conventional CPU. 1 Developing means 2...Toner replenishment detector 3...Toner concentration detection means 3a...Toner concentration detector 4...CPU 4a...CPU storage device 4b...CPU arithmetic unit 4C... CPU control device 7...Photosensitive image support 12...Photosensitive drum 22...L/car cartridge

Claims (1)

[Scope of Claims] A developing means containing a two-component developer; a replenishing means for replenishing the developing means with toner of the developer; detecting a toner specific concentration of the developer in the developing means; a density detecting means that outputs a voltage according to the toner density detecting means; and a toner replenishment start voltage and toner replenishment stop voltage corresponding to the input voltage and the set value of the developer in the developing means. voltage, and when the output voltage is higher than the toner replenishment start voltage, the replenishing means is controlled to replenish toner, and when the output voltage is lower than the toner replenishment stop voltage, the toner replenishment of the replenishing means is stopped. A control means for controlling the humidity of the developing means and a humidity detecting means for detecting the humidity of the developing means are provided, and a voltage outputted in response to the humidity detection by the humidity detecting means is inputted to the control means, and the toner of the set value is inputted to the control means. For the replenishment start voltage and toner replenishment stop voltage, respectively.
An image forming apparatus that controls the start or stop of toner replenishment using a voltage that is the sum of a voltage that increases or decreases in response to changes in humidity.