JPS6034751B2 - Developer remaining amount detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting the amount of developer remaining in a container for replenishing developer.

For example, in a dry type developing device for electrophotography, it is necessary to replenish as much toner as is consumed by copying in order to maintain a constant image density. For this purpose, it is necessary that the container for replenishing the developer always contains the developer, and when the developer runs out, it is necessary to immediately detect and replenish the developer. However, since the dry developer tends to solidify inside the container, it is difficult to accurately detect and display the amount of developer remaining in the container. For this reason, attempts have been made to make the container transparent and visually detect the remaining amount, but since constant monitoring is not possible, it is not always possible to appropriately detect the remaining amount. SUMMARY OF THE INVENTION An object of the present invention is to provide a device that solves the above problems and automatically and correctly detects the remaining amount of developer.

The object of the present invention has been achieved by magnetically detecting the remaining amount of developer using an electromagnetic coil.

Generally, as shown in FIG. 1, a developer replenishment device that discharges developer from a discharge section 3 provided below the container 2 while rotating a container 2 containing developer 1 in the direction indicated by an arrow decreases the amount of developer. As it moves, it gradually falls downward due to gravity.

The developer that falls and accumulates at the bottom of the container 2 is scooped up by the dispenser tube 4, and once placed in the tube 4, is sent out while being mixed by the rotating body 5. As a dry developer, a magnetic developer is generally used, such as a developer containing a magnetic carrier such as iron powder, or a developer in which toner itself is magnetic.

Therefore, if the detection coil 6 constituting an oscillator is provided opposite the part of the container 2 that is the lowest developer pool, the inductance of the coil will change according to changes in the remaining amount of developer, and the oscillation frequency will change. , the remaining amount of developer can be detected from this oscillation frequency. However, if the remaining amount of developer is small, the dispensing tube 4, which scoops up the developer while swirling, often temporarily becomes hollow immediately after passing through.

Generally, the dispenser tube 4 is configured to scoop out the developer from the lowest part of the pool, but if the detection coil is placed opposite to the position where the scoop part of the dispenser tube 4 passes, Each time, the remaining amount is temporarily displayed as zero, and there is a risk of misunderstanding the remaining amount. Also rotating dispenser tube 4
If the sensor stops at a position exactly facing the detection coil, there is a risk of false detection. An object of the present invention is to prevent false detections.

The present invention solves this problem by using a detection coil 6 as shown in FIG.
This was achieved by locating the replenishment device 4 at a location remote from the replenishment action position of the dispenser tube 4. Since the position of the detection coil 6' is away from the working position of the dispenser tube 4, it is not affected by the cavity after passing, and the remaining amount can always be accurately detected no matter where the dispenser tube 4 is stopped. Became.
Considering the developer replenishment effect, it is best to select a position for the detection coil 6' that is slightly upwardly shifted toward the bag of the container from the scooping position of the dispenser tube 4. The figure shows an example where the container is tilted, but even in a system where the container is placed vertically and a replenishing device takes out developer from the bottom of the container and replenishes it to the developing device, the detection coil is placed slightly above the replenishing device. The same effect can be achieved by

As a detection circuit using the detection coil 6', a circuit as shown in FIG. 2 can be used. The detection coil 6' is coil L.
The oscillation frequency obtained by changing the inductance of the coil according to the change in the remaining amount of developer is used as the coil L of a Colpitt type sine wave oscillator A consisting of capacitors C1 and C2 and transistor Q. Detect changes. The output of the oscillator A is inputted via a coupling capacitor C3 to an FM demodulator B, which includes a phased-oct loop integrated circuit NE56 (trade name of Signetics), a variable resistor VRI, and a capacitor C4. The output of demodulator B is buffered by amplifier C and outputted via integrator D as a remaining amount detection signal. With this device, the remaining amount of developer can be detected easily and accurately.

[Brief explanation of the drawing]

FIG. 1 is a general front view of a device for detecting a developer device in a developer supply container using a detection coil, FIG. 2 is a front view of a device according to the present invention, and FIG. 3 is a diagram showing an example of a detection circuit. It is. 1... Developer, 2... Container, 3...
...Discharge section, 4...Replenishment device, 6...
・Detection coil. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a device that detects the remaining amount of developer in a developer container as a change in oscillation frequency using a detection coil provided on the outer surface of the container, the developer is sent out by a developer replenishing device that rotates from the container reservoir, and the center of the detection coil is located at the developing area. What is claimed is: 1. A developer remaining amount detecting device, characterized in that the device is disposed above and near a feeding position of a developer replenishing device.