JPS5922071A - Developer deterioration detector - Google Patents

Abstract

PURPOSE:To detect the deterioration of a powder developer accurately, by providing a developer resistance detecting means consisting of a high frequency power source and counter electrodes for detecting variation in the resistance of the developer. CONSTITUTION:A detection coil is inserted in a toner density detector 10 and a toner density variation signal based upon variation in the inductance of the coil is supplied to a control part 15 and compared with a reference value, when the signal is lower than the reference value, a density decrease signal is outputted to rotate a supplementing roll 14 to hold the toner density constant. The counter electrodes 11 fitted in parallel to the flow of the developer are impressed with a constant voltage from the high frequency power source 16 and the AC voltage across a resistance R connected in series is rectified 17 and compared by a comparator 18 with a threshold level Vs. Thus, as the resistance between the counter electrodes 11 increases, a DC voltage V drops and when it drops below the level Vs, a comparator 18 operates to display the deterioration of the developer.

Description

[Detailed Description of the Invention] C] Technical Field of the Invention The present invention relates to (1) a developing device of a printing device d such as a droplet recording device, and in particular detects deterioration of powder developer consisting of toner and carrier. The present invention relates to a developer deterioration detection device suitable for.

(LL) Backbone of technology In recent years, electronic! +'? With the increasing oil consumption of machines, output devices such as line printers are required to have the following features.

(1) High-speed printing (2) Miniaturization of the device (3) Easy maintenance (4) No noise In order to meet these requirements, research and development of non-imbat type line printers is underway.

(C) Prior Art and Problems Conventionally, an electrostatic image formed on a latent image forming medium in a printing device using the IT T4 process, etc., uses a powder developer consisting of carrier r and toner. Development is performed by magnetic brush development.

In such a powder developer composed of carrier and toner, only the toner is consumed when development is performed. For this reason,
A constant print density is achieved by detecting the toner concentration in the developer and controlling the toner concentration to be constant.

However, if you use it for a long time, the carry f.

H is a drawback that a constant print density cannot be obtained due to fatigue development such as toner sticking around A, and print quality deteriorates.

For this reason, conventionally, during a predetermined operation, no.

Although the developer is replaced with a new one every time printing is completed, this method is not consistent due to variations in the developer and the usage conditions of the printing device, so it is difficult to know when it is time to replace the developer. was not appropriate.

(IJ) Purpose of the Invention In view of the above-mentioned drawbacks, the purpose of the present invention is to prevent the deterioration of the developer, especially the deterioration of the L1 print quality due to the adhesion of l-f- to the carrier surface, and to prevent changes in the electrical impedance of the present developer. It is an object of the present invention to provide a '9i developer deterioration detection device that can detect the deterioration of the developer and accurately determine when to replace the developer.

(g)) According to the present invention, a powder developer comprising a toner and a carrier that visualizes a latent image on a latent image forming medium, a toner of the powder developer A density detection means for detecting the density, a density control means for keeping the toner concentration in the powder developer constant based on a toner concentration signal detected by the density detection means, a counter electrode and a high frequency 1 for detecting a resistance change of the powder developer. [i 1fli! A developer resistance detection means consisting of.

This is achieved by providing a developer deterioration detection device characterized by the following features:

0P) Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment in which the present invention is implemented in a developing device.

Reference numeral 1 designates a photosensitive drum, on which an electrostatic latent image is formed by a latent image forming means (not shown), the electrostatic latent image is visualized by a developing device, and is further printed on printing paper by a transfer device +u (not shown). It is something that

2 is the side plate of the developing device, 8 is the developer, which is a powdered developer containing a mixture of toner and carrier, and 04 is the transport mug IU-
, 5 indicates l1lt (Magroll for I.21hI4
The developer 8 is increased by (14) by the mag rolls 4 and 5.
When it comes into contact with the surface of the photosensitive drum 10, 'U t! f+ Ttj image is being developed. A scraping plate 6 is used to adjust the height of the magnetic brush of the developing mag roll 5. Seven partition plates are used to return the developer after development to the stirring section. Reference numeral 8 denotes a single roller for stirring the developer collected by the partition plate 7 and the newly replenished toner to achieve a uniform toner concentration. 9 is a gate, which is used to constantly supply a well-stirred developer to the mag roll section. .1O is a toner concentration detector, which detects the coil's interface by inserting a coil into the developer and changing the mix ratio of toner and gear as the toner concentration changes. This method detects L″C to J---θ degrees by utilizing changes in the ductance value.

11 is a counter electrode, ? life! A few kl between jii
Jz~Enemy image 1 (117, applying high Rd wave 1uH-,
111 due to developer deterioration. This detects changes in atmospheric impedance. Note that the toner concentration detector 10 and the counter electrode 11 are provided near the gate 90 where the flow of the developer 3 is stable and there is almost no change in LIL force.

12 is the toner hopper, 13 is the toner, and 14 (-↓toner supply roller is the toner supply roller.
When the toner concentration 191 is lowered by the fc multiplier detected by +, it rotates by one gal and replenishes new toner. In addition to impedance increasing due to developer deterioration, it also changes due to changes in toner concentration and developer pressure. Therefore, in order to detect developer deterioration as a change in impedance, it is necessary to control the toner concentration constant and Detection must be performed under conditions where the flow of the current rqI agent is stable and pressure changes are small. In the embodiment shown in the figure, in order to keep the toner density constant, the toner density of the developer is expressed as t%Ill by changing the inductance of the coil, but other detection means may also be used.

FIG. 2 is a diagram showing an arrangement 1 of the detection section of FIG. 1. In the figure, a detection coil is inserted into the toner concentration detector 10, and a change in the inductance of this detection coil outputs an i-toner concentration signal to control 15H)l! 1.
5-\Enter.

The human-operated control unit 15 of the toner concentration change number d compares the toner γg strength change signal with the reference number j1r, and outputs the D degree decrease number if it is lower than 1[1]. First
As shown in the figure, the toner replenishing roller 14 is rotated to keep the I/toner density constant.

The opposing Mj pole 11 is placed parallel to the flow of the developer so as not to obstruct the flow of the developer, and a constant 1h pressure is applied by the high frequency 1 [it; Resistor) t is connected.

AC voltage across this resistor! 1 by the I-current circuit 17
By converting it into h flow pressure and comparing the thread and shoulder levels VS with a comparator, it is found that if the developer deteriorates and the resistance between the opposing electrodes 11 increases, 5IF (, flow 11
1. Pressure V, tension, scratches, short relief VB -1
.times., the comparator 18 operates, and this output can be used to instruct replacement of the developer due to deterioration by, for example, lighting an indicator lamp or the like.

FIG. 3 is a diagram showing the locality of the circuit of FIG. 2.

The figure shows a state in which the impedance of the 3A developer increases due to deterioration of the developer, and the 1uLEV decreases and increases.

(As explained in detail about the invention, according to the invention, (1) The failure period due to deterioration of the developer can be detected immediately.

(2) Since the deterioration of the developer can be detected during the operation of the developing device, there is no need for troubles such as non-printing.

This effect can be expected.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment in which the present invention is implemented in a developing device. 21st Jijfl! l l no m knowledge fllic7Jt[
Figure showing llll. FIG. 3 is a diagram showing a customization of the circuit of FIG. 2. ■...Photosensitive drum 2...Currently 1ψdS side plate 3...
・Developer 4...Mag roll for transport 5...Mag roll for image 1 6...Scraping plate 7...Partition plate 8
...Shixing roller 9...Gate 10...
Toner concentration detector 11... Opposed r pressure 12... Toner A2 bar 13... Toner 14... To p-
hH'i roller 1b...Control unit ■6...High frequency 1
"Source 17...e iAE Circuit 18...Comparator 4: Kaya I21 Kaya 3I21 □ Genzu Illusion 11 end d Ihi sword (

Claims (1)

[Claims] A powder developer consisting of toner and carrier that visualizes the latent image on the latent image type I medium, a degree detection means for detecting the toner concentration of the powder developer, and a toner m14 degree signal detected by the density detection means. Concentration control means for keeping the toner concentration in the powder developer constant; opposing HLtI! for detecting resistance fading of the powder developer; Developer deterioration detection device i'10, characterized in that it comprises developer resistance detection means consisting of i+, high frequency 11/, and a source.