JPS6027031B2 - Toner concentration detection device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a toner concentration detection device.

Powder developers are often used as developing devices in fin photographic devices and the like.

. Powder developer is generally a mixed powder of magnetic carrier and toner, and during development, this developer is conveyed to the latent image by a bucket or magnetic roll. Although the developer is consumed in the development process, most of the consumption is toner, and most of the magnetic carrier remains and is reused. Therefore, the toner in the developer
The concentration gradually decreases. On the other hand, in order to maintain good and stable development characteristics, it is desirable that the toner concentration in the developer be constant. Therefore, toner concentration detection is performed for toner replenishment. To detect this toner concentration, a device uses the fact that the magnetic properties of the developer change when the toner concentration changes, and measures the toner concentration by applying the developer to a magnetic sensing element such as a coil. is being played. Such toner concentration detection devices have problems such as nonuniform characteristics of the magnetic sensing element (coil) and electric circuit elements themselves, and assembly errors when assembled to the developing device, which greatly affect detection accuracy. Therefore, it is desirable that this type of detection device be able to be easily adjusted while it is assembled in the developing device. SUMMARY OF THE INVENTION An object of the present invention is to propose a toner concentration detection device that can be easily adjusted while assembled in a developing device.

In the present invention, a detection container through which the developer to be measured passes is provided with a developer inlet, a developer outlet, and an adjustment sample introduction port, and the adjustment sample is introduced while assembled in the developing device to inspect and adjust the characteristics. It is characterized by the fact that it is possible to do so.

The following description will be given based on the embodiment shown in the drawings. In FIG. 1, 1 is a pair of side plates, and a substantially U-shaped bottom plate 2 is sandwiched between them to form a developer container in which a developer 4 is stored. ing. 3 is a spouter for assembling the side plate 1 and the bottom plate 2 in a constant dimensional relationship.

Reference numeral 5 denotes a roll magnet fixed between the side plates 1, and a non-magnetic sleeve 6 rotatably supported by external power is provided on the outer periphery of the roll magnet.

The side of the roll magnet 5 facing the latent image drum 20 is magnetized. A screw 7 is supported between the side plates 1 so as to rotate in synchronization with the sleeve 6, and it illuminates the developer 4 at the bottom of the developer container to homogenize the mixture of carrier and toner and to reduce toner friction. Gives a charge.

A top cover 8 is engaged with a top cover pin 9 attached to the side plate 1, and is rotatably supported as shown by the chain line.

Reference numeral 10 denotes a substantially rectangular cylindrical detection container, which has a developer inlet 11 at the center side, a developer outlet 12 at the bottom side, and an adjustment developer inlet 13 at the upper end.

This detection container 10 has a developer inlet 11 and a developer outflow row 2 formed on the side wall of the bottom plate 2, and is attached to the outer surface of the bottom plate 2 so as to coincide with the windows 2a and 2b. 4 from adhering. Also, the bottom plate 2
Adjustment developer inlet 13 of the detection container 10 attached to the
is closed by the top cover 8. A detection coil 14 is installed between the developer inlet 11 and the developer outlet 12 so as to surround the detection container 10 .

15 is a guide plate for guiding the developer 4 on the outer periphery of the sleeve 6 to the developer inlet 11 of the detection container 10;
It is removably attached to a support metal fitting 16 fixed directly under a.

17 protects the detection coil 14 and the detection container 10 from mechanical external force and electrically and magnetically protects it from the outside;
It is a side cover.

18 is a roll magnet having a plurality of magnetic poles on the circumference, and window 2
It is supported between the side plates 1 so as to rotate synchronously with the sleeve 6 on the inside of the sleeve 6.

This roll magnet 18 does not need to exist over the entire width between the side slopes 1, but only needs to exist in the area facing the window 2b.
Note that 19 indicates a funnel attached to introduce a preparation sample into the detection container 10. In Figure 2, 30
is a constant frequency oscillator that generates a sine wave or a periodic function number wave, and its output is connected to the amplifier 31 and the feed stage capacitor 32.
is applied to the detection coil 14 via.

The detection coil 14 and the coupling capacitor 32 are set to a constant close to resonance with respect to the frequency generated by the constant frequency oscillator 30. The terminal voltage of the detection coil 14 is rectified by a rectifier 33,
It is connected so that it is smoothed by a smoothing circuit 34 and applied to an output resistor 35. 37 is a differential amplifier, which has a reference voltage Vs given from a potentiometer 36 and an output resistor 35.
The state of the voltage is compared, and an output voltage Es approximately equal to the voltage of the power supply 39 is output in the state of VoSVs.

Incidentally, the output voltage Vo with respect to the toner concentration C (%) of the developer has the appearance shown in FIG. When the concentration drops to 3%, the differential amplifier 37 outputs Es. In the above configuration, when the developing device is in operation, the sleeve 6, the screw 7,
The roll magnet 18 and the latent image drum 20 each rotate in the direction of the arrow.

The developer 4 at the bottom of the developer container is attracted to the sleeve 6 by the magnetic force of the roll magnet 5, forming a magnetic brush 4a.
The magnetic brush 4a moves in the same direction as the sleeve 6, and its tip gently brushes against the latent image drum 20 to perform development.
When the magnetic brush 4a moves further, the roll magnet 5 passes through the adhesion area and the magnetic attraction force weakens, causing the magnetic brush 4a to collapse and naturally fall to the bottom of the developer container. However, a portion of the developer 4 is transferred from the surface of the sleeve 6 onto the guide plate 15 and enters the detection container 10 through the developer inlet 11. The developer 4 that has fallen inside the detection container 10 is attracted by the roll magnet 18 and is discharged from the developer outlet 12 into the developer container. By setting the rotational peripheral speed of the roll magnet 18 so that the discharged amount is smaller than the amount introduced into the developer inlet 11, the detection container 10 is filled with the developer 4, and the excess developer 4 is falls from both sides of the guide plate 15. Therefore, the density of the developer 4 in the detection container 10 is stable, and the inductance of the detection coil 4 changes at a stable value in inverse proportion to the toner concentration. Further, when the development is stopped, the sleeve 6 stops and the developer 4 flowing into the detection container 10 from the inlet 11 disappears, but the roll magnet 18
Since the rotation of the detection container 10 also stops, no developer 4 is discharged from the outlet 12, and the inside of the detection container 10 does not become blank.
Note that when the roll magnet 18 stops rotating, the developer 4 near the outlet 12 is magnetized and stops in a chain state, so the developer 4 in the detection container 10 does not naturally flow out. In this state, the toner concentration (magnetic carrier) of the phenomenon agent 4 acts on the detection coil 14, changes the inductance of the detection coil 14, and changes the terminal voltage Vo of the output resistor 35 with the characteristics shown in FIG.

This voltage yo is compared with a reference voltage Vs provided by a potentiometer 36 by an amplifier 37, and an output voltage Es is produced when the toner concentration decreases to a set value.
Therefore, by operating the valve using the world voltage Es to replenish toner, the toner concentration can be maintained within a desired range. By the way, when adjusting such a developing device when assembling, the top cover 8 is opened, the funnel 19 of the adjustment sample introduction port 13 at the upper end of the detection container 10 is inserted, and the developer 4 with the lower limit toner concentration is poured. The detection container 10 is filled.

At this time, the roll magnet 18 is stopped, removed from the guide plate 15, and the excess developer 4 overflows from the developer inlet 11. can reproduce the fullness of Therefore, if the potentiometer 36 is adjusted in this state so that the voltage yo of the output well 35 and the reference voltage Vs are equal, the toner concentration detection device can be adjusted without operating the developing device. In addition, when readjusting during maintenance and inspection, please refer to the guide plate 1.
5 and rotate the roll magnet 18, the detection container 10
Since the residual developer 4 inside is discharged, the same adjustment work as described above can be performed after that.

Therefore, it is not necessary to fill the entire area of the developing device with an adjustment sample (developer) during assembly or maintenance and inspection, so that economical adjustment work can be performed.

Note that the adjustment material does not need to be a developer (powder), and may be a solid material (integral) that has a magnetic effect comparable to a predetermined toner concentration. Since the entrusted detection container 10 has the adjustment sample introduction port 13 formed on its upper end surface, it can be removed from the mold, and therefore resin molding becomes easy.

As described above, according to the present invention, it is possible to propose a toner concentration detection device whose characteristics can be easily adjusted while being assembled in a developing device.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a longitudinal sectional side view of a developing device, FIG. 2 is an electrical connection diagram, and FIG. 3 is a characteristic curve diagram. 4...Developer, 4a...Magnetic brush,
6...Sleeve, 10...Detection container,
11...Developer inlet, 12...Developer outlet, 13...Adjustment sample introduction port, 14...Detection coil. Figure 3 Tsutomu-Figure Z

Claims (1)

[Claims] 1: a conveyance means for conveying a developer containing a magnetic carrier and toner contained in a developer container; a detection container through which at least a portion of the developer conveyed by the conveyance means is introduced; The detection container includes a magnetic sensing element that responds to a magnetic carrier in the developer passing into the detection container, and detects the toner concentration in the developer based on the signal from the magnetic sensing element. , the detection container is a cylindrical body, and has a developer inlet opening at the middle part of its side surface for introducing the developer transported by the transport means, and a developer inlet opening at the lower part of the developer inlet opening to introduce the developer transported by the transport means. A developer outlet for allowing the developer to flow out into the developer container, and an adjustment sample introduction port for introducing the adjustment sample by opening at an upper end surface, the developer container having a developer outlet facing the developer outlet. 1. A toner concentration detecting device, comprising: a roll magnet; and a top cover for closing said adjustment sample inlet at the top of said developer container.