JPS6227392B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner concentration detection device.

Conventionally, a sensor as shown in FIG. 1 has been considered as a sensor for measuring the toner concentration of a two-component dry developer consisting of toner and carrier based on its fluidity. That is, a funnel 3 is provided in which an orifice portion 1 having a predetermined diameter and a dovetail-shaped holding portion 2 located above the orifice portion 1 and expanding upward are integrally formed. A pipe section 4 having an inner diameter larger than the inner diameter of the orifice section 1 is vertically attached, and a coil 5 is wound around the outer circumference of the pipe section 4. An oscillation circuit 6, a frequency counter 7, and a comparison circuit 8 are connected in this order to this coil 5, and a toner replenishment circuit 9 is connected to this comparison circuit 8.

Therefore, the developer 1 supplied into the holding section 2
0, the flow rate is limited in the orifice section 1 based on its flow rate, but since the flow rate changes depending on the toner concentration, the amount of carrier of the developer 10 flowing down in the pipe section 4 changes, and the amount The oscillation frequency in the oscillation circuit 6 made up of the coil 5 changes accordingly. This frequency is counted by a frequency counter 7 and compared with a reference value in a comparator circuit 8, and when it becomes lower than a predetermined reference value, it is determined that the toner concentration is low, and the toner replenishment circuit 9 is driven. Toner is replenished until the toner concentration in the developer 10 reaches a predetermined value.

However, such a structure has the following problems. That is, developer 10
When the toner concentration becomes high and the fluidity deteriorates, or when a large amount of the developer 10 flows into the orifice part 1 at once, a crosslinking phenomenon of the developer 10 occurs in the holding part 2, and the orifice part 1 becomes clogged. The developer 10 may stop flowing down.

Therefore, one possible method for preventing clogging is to mask the inlet of the developer 10 in the holding section 2. However, although this method can prevent clogging caused by a large amount of developer 10 flowing into the orifice portion 1 at once, if the toner concentration of the developer 10 increases from, for example, 2.5 wt% to 3 wt% or more, clogging occurs at once. Even if there is not a large amount of flow, clogging occurs frequently. It is also conceivable to increase the diameter of the orifice portion 1, but although this measure can reduce the frequency of clogging, it cannot completely eliminate clogging.

The present invention has been made in view of these points, and an object of the present invention is to provide a toner concentration detection device that has a simple structure, eliminates the cross-linking phenomenon of developer, and does not cause clogging. .

The present invention provides a funnel consisting of an upwardly expanding holding part that holds a developer and an orifice part of a predetermined diameter located at the lower end of this holding part, and a funnel that communicates with the orifice part of the funnel from below and that is connected to the orifice part of the funnel from below. A sensor formed by integrally combining a pipe portion with a larger inner diameter and a coil wound around the outer periphery of the pipe portion, a striking device that vibrates the sensor, and a toner to which the coil is connected. The present invention is characterized in that it comprises a concentration detection circuit, and the flow rate of the developer freely falling from the funnel is detected as a change in magnetic permeability by the detection circuit. Therefore, when the flow rate of the developer freely falling from the funnel is detected as a change in magnetic permeability by the detection circuit, by striking the sensor funnel with a striking device, the flow rate at the orifice of the funnel can be detected. It is possible to prevent clogging of the developer due to the crosslinking phenomenon, and it is possible to accurately detect toner concentration.

Embodiments of the present invention will be explained based on FIGS. 2 and 3. Components that are the same as those shown in FIG. 1 are designated by the same reference numerals, and description thereof will be omitted. First, a photoreceptor drum 11 which is formed into a drum shape and rotates in one direction is provided, although only a portion thereof is shown, and a developing device 12 is provided at the lower left of the photoreceptor drum 11. This developing device 12 includes a container 13 for storing a two-component dry type developer 10, and the photosensitive drum 11.
A sleeve 14 that rotates in close proximity to the sleeve 14, a sleeve 15 below the sleeve 15, a scraping plate 16 that scrapes the developer 10 from the surface of the sleeve 14 and flows down, and a scraping plate 16 that is held by the scraping plate 16.
The sensor 17 shown in FIG.
and stirring blades 18 and 19 for stirring the developer 10 in the container 13.

In the vicinity of the sensor 17, there is a striking device 20 that intermittently vibrates the sensor 17.
is provided. That is, this striking device 20
An arm portion 22 is rotatably attached to the stirring blade main shaft 21 by a bearing or the like to rotate the stirring blade 18 by a drive mechanism (not shown), and an arm portion 22 is connected to one end of this arm portion 22 and faces the sensor 17. The striking part 23 and the scraping plate 1
A saucer 2 that receives the developer 10 flowing down along the
4 is connected to the other end of the arm portion 22.

In such a configuration, the developer 10 is delivered to the photoreceptor drum 11 by rotation of the sleeve 14, and the toner in the developer 10 is transferred to the photoreceptor drum 11 according to the electrostatic latent image formed on the photoreceptor drum 11.
The excess developer 10 is scraped off by the scraping plate 16, and a part of it is scraped off by the scraping plate 16.
7 Falling upwards. Therefore, as shown in FIG. 1, if the toner concentration is low, toner is replenished until the toner concentration reaches a predetermined value.

Here, in the sensor 17 section, the holding section 2
A certain amount of developer 10 is deposited on the orifice part 1.
flowing down from At this time, a crosslinking phenomenon of the developer 10 may occur at the lower end of the holding section 2, but a portion of the developer 10 flowing down along the scraping plate 16 is deposited onto the receiving tray 24 connected to the arm section 22. If the developer 10 deposited on the tray 24 exceeds a predetermined weight, the striking device 20 loses its balance and rotates about the stirring blade main shaft 21 (dotted line in Figure 2). As a result, the striking portion 23 collides with the sensor 17, causing the sensor 17 to vibrate. The developer 1 is in a crosslinked state due to the vibration of the sensor 17.
Each of the 0 carriers moves in a direction that makes it easier for them to move, with some carriers moving downwards and others moving upwards, causing the bridge to loosen and eventually break. When the crosslinking is broken in this manner and the developer 10 flows into the orifice portion 1, it continues to flow for several tens of seconds or more. this number
10 seconds corresponds to copying three or more A4 size sheets during continuous copying, but clogging can be prevented by limiting the number of hits to the sensor 17 to one per copy. However, the number of hits is 1
If the rate is more than 3 times per second, the flow rate of the developer 10 will be disturbed, making it impossible to measure the toner concentration accurately, and since the flow of the developer 10 will stop at the moment of impact, the accuracy of toner concentration measurement will be improved. To do this, the detection may be stopped at the timing of the impact.

On the other hand, along with the striking operation of the striking part 23, the receiving tray 2
The developer 10 on this tray 24 also rotates and tilts.
flow down. After the developer 10 is removed from the tray 24 in this way, the striking device 20 rotates around the stirring blade main shaft 21 and returns to the original position shown by the solid line. This series of operations is repeated intermittently while the developer 10 is drawn up by the rotation of the sleeve 14. The cycle of this operation is determined by the size of the tray 24, the amount of developer 10 scraped off by the scraping plate 16, and the like.

Note that in the configuration shown in FIGS. 2 and 3, since the sensor 17 is struck, it may have a negative effect on the durability of the sensor 17, but the striking part 23 has rubber or other material on its tip. The elastic body may be detachably attached so that it can be replaced in case of damage. Also, sensor 17
As for the side, if it is fixed to the scraping plate 16 with screws or the like, the screws may loosen due to impact, so welding or adhesive attachment may be used. However, even if the sensor is attached by welding or the like, if it is attached to a single sensor support plate 25, the sensor support plate 25 may gradually warp upward due to impact.
As shown in FIG. 4, if a reinforcing plate 26 is welded to the side surface of the sensor support plate 25, it will not be deformed and will be even better. Also, since a part of the sensor 17 may be dented at the part where the striking part 23 collides, the thickness of that part may be increased or a replaceable protective plate held by the rail 27 as shown in FIG. This can be prevented by means such as providing 28.

Furthermore, in order to ensure the appropriateness of the rotational movement of the striking device 20, that is, the appropriateness of the relationship between the tray 24 and the amount of developer 10 deposited on the tray 24, it is necessary to In this position, the tray 24 is set to be tilted slightly upward, and the developer 10 is
When the saucer 24 is tilted due to the weight of
As shown in FIG. 7, a lid 31 biased by a spring 30 is provided on the side of the tray 24 where the developer 10 flows down;
The lid 31 may be opened by a certain weight of the developer 10.

Next, FIG. 8 shows a second embodiment of the present invention. In this embodiment, a striking rod 32 having a striking portion 23 at the tip is rotatably attached to one end of an arm portion 22 rotatably attached to a main shaft 21, and a long hole is formed at the rear end side of the striking rod 32. 33 is engaged with one end of a fixed rod 34 to constitute a striking device 35. Note that 36 is a stopper for the saucer 24.

Even in such a configuration, if the amount of developer 10 that has flowed down onto the tray 24 along the scraping plate 16 exceeds a predetermined amount, the arm portion 22 will move around the main shaft 21.
rotates, pushing up the striking rod 32 and rotating it.
As a result, the striking portion 23 collides with the sensor 17, causing the sensor 17 to vibrate. Therefore,
Even if a crosslinking phenomenon occurs in the holding part 2, the crosslinking can be broken and clogging can be prevented.

Further, FIG. 9 shows a third embodiment of the present invention, in which the striking device 37 uses the principle of Shishi-odori, and the striking part 23 is placed in its original position, and the sensor 17
The spring 38 is connected to the arm portion 22.

In such a configuration, when the amount of developer 10 that has fallen onto the tray 24 exceeds a predetermined amount, the main shaft 21
The arm portion 22 rotates counterclockwise around , and the striking portion 23 separates from the sensor 17. However, since a spring 38 is attached to the arm portion 22, the arm portion 22 counterclockwise rotates due to the spring 38, and the striking portion 23 collides with the sensor 17. As a result, even if a crosslinking phenomenon occurs, it is broken and no clogging occurs.

Furthermore, FIG. 10 shows a fourth embodiment of the present invention, in which an arm portion 22 between a main shaft 21 serving as a rotation center and a striking portion 23 as a striking device 39 is shown.
A part (or all) of the spring 40 is formed, and one end of the spring 40 is engaged with a stopper 41 that rotates in only one direction.

In such a configuration, when the tray 24 is tilted by the developer 10 that has fallen onto the tray 24, the spring 40 is warped as shown by the dotted line, and the contact area between the tip and the stopper 41 gradually decreases, and the spring 40 is bent to a certain extent. If it warps, it will eventually come off the stopper 41 and the striking portion 23 will be actuated in a reactionary manner by the elasticity of the spring 40. This gives vibration to the sensor 17 and prevents clogging. Then, after the striking action and the developer 10 flowing down on the tray 24, the tray 24 returns to its original position. At this time, when the tip of the spring 40 side rotates downward, the stopper 41 is rotated counterclockwise, and the engagement relationship between the tip and the stopper 41 is shown by a solid line.

Note that the matters shown in FIGS. 4 to 7 are taken into consideration in the second to fourth embodiments as well.

Furthermore, in these embodiments, the impact devices 20, 35, 37, and 39 each having a receiving tray 24 are used, and the weight of the developer 10 that has fallen onto the receiving tray 24 is used as the operation source for the impacting operation. It may also be operated by a cam or the like connected to.

As described above, the present invention includes a funnel consisting of an upwardly expanding holding part that holds developer and an orifice part of a predetermined diameter located at the lower end of this holding part, and a funnel that communicates with the orifice part of this funnel from below. A sensor including a pipe portion having an inner diameter larger than the orifice portion and a coil wound around the outer periphery of the pipe portion are integrally coupled; a striking device that vibrates the sensor; It is connected to the toner concentration detection circuit,
Since the fluidity of the developer freely falling from the funnel is detected by the detection circuit as a change in magnetic permeability, the fluidity of the developer freely falling from the funnel is detected by the detection circuit as a change in magnetic permeability. By striking the sensor with a striking device, it is possible to prevent clogging of the developer due to cross-linking at the orifice of the funnel of the sensor, thereby making it possible to accurately detect toner concentration. This has the effect of making it possible.

[Brief explanation of the drawing]

FIG. 1 is a vertical side view showing a conventional example, FIG. 2 is a vertical side view showing a first embodiment of the present invention, and FIG.
The figure is a perspective view, FIG. 4 is a partially improved perspective view, FIG. 5 is a vertical side view, FIG. 6 is a side view, FIG. 7 is a side view, and FIG. 8 is a second view of the present invention. FIG. 9 is a side view showing a third embodiment of the invention, and FIG. 10 is a side view showing a fourth embodiment of the invention. 1... Orifice part, 2... Holding part, 3... Funnel, 4... Pipe part, 5... Coil, 17...
Sensor, 20... hitting device, 35... hitting device, 37... hitting device, 39... hitting device.

Claims (1)

[Scope of Claims] 1. A funnel consisting of an upwardly expanding holding part that holds developer and an orifice part of a predetermined diameter located at the lower end of this holding part, and communicating with the orifice part of this funnel from below. A sensor configured by integrally combining a pipe portion with an inner diameter larger than the orifice portion and a coil wound around the outer periphery of the pipe portion, a striking device that vibrates the sensor, and the coil connected. What is claimed is: 1. A toner concentration detection device comprising: a toner concentration detection circuit, wherein the detection circuit detects the fluidity of the developer freely falling from the funnel as a change in magnetic permeability.