JPH0348266A - Toner end detection and toner supplying device - Google Patents

Abstract

PURPOSE:To accurately perform toner end detection and toner supply by making a toner end display when it is judged again that toner runs short after toner is supplied for a certain time when the output of a toner detection sensor is compared with a predetermined value and larger. CONSTITUTION:A timer circuit 26T counts the detection signal of a toner detection sensor 23, i.e. the time (t) or the number (n) of pulses corresponding to the time and a comparator compares the number (n) with the predetermined no-toner value tA or nA and judges the toner end state when t>tA or n>nA. Further, a CPU 26 turns on a clutch mechanism 24 and supplies toner from a toner cartridge 10 to a developing device 11. When the toner detection sensor 23 detects the toner end state after toner is supplied for the certain time and then judges the toner and again, the clutch mechanism 24 is turned off to make the toner end display when a laser printer is in printing operation or stop a driving motor 25 and then makes the toner end display when not. Consequently, the toner end detection and toner supply are accurately performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Technical Field) The present invention relates to a toner end detection and toner supply device for an image forming apparatus using an electrophotographic process such as a copying machine, a facsimile machine, and a printer. (Prior Art) FIG. 4 is a sectional view showing the configuration of a laser printer as an example to which the present invention is applied.

To briefly explain this operation, the recording paper 2 in the paper feed cassette 1 is separated one by one by the feed roller 3 and the corner claw 4, and then transferred to the image writing section above (in the direction of arrow A) by the intermediate roller pair 5. Transported. On the other hand, the surface of the photoreceptor drum 7 is charged by the charger 6, and the optical writing unit 8
The electrostatic latent image formed on the photoreceptor drum 7 at the optical writing position 9 is developed by the developing device 11 in the toner cartridge 10 to form a toner image (visible image), and then the electrostatic latent image is formed on the photosensitive drum 7 at the optical writing position 9. The image is transferred onto the fed recording paper 2 by the transfer charger 13. After the transfer, the excess charge on the recording paper 2 is eliminated by the static elimination brush 14, and the recording paper 2 separated from the photoreceptor drum 7 is
The recording paper is conveyed to a fixing unit l6 by a suction fan l5, where it is fixed and ejected to a paper ejection tray 17.

On the other hand, toner remaining on the photosensitive drum 7 is cleaned by a cleaning unit l8. Furthermore, the charge on the photosensitive drum 7 is removed by a static eliminator 19 in preparation for the next operation process. In the above laser printer, the parts to which the present invention is applied are the toner cartridge IO and the developing device 11. This developing device includes a developing roller 20, a toner supply roller 21 that supplies toner from a toner cartridge 10 separated from the developing device 11 to the developing device 11, and rotates in one direction at a constant cycle to stir the toner in the developing device. The toner agitating member 22 is provided with a toner stirring member 22, and a piezoelectric vibration type toner detection sensor 23 that detects the presence or absence of toner.

(Problem to be Solved by the Invention) In the developing device 11, the toner detection sensor 23 detects the presence or absence of toner, and when there is toner, the image shown in FIG. 3 (1) is detected.
A detection signal (H) of a certain level is output as shown in
When there is no toner, a unique oscillation frequency f is output as a detection signal as shown in FIG. 3(2). Based on this detection signal, the main body CPU determines the presence or absence of toner and drives the toner supply roller 21 to supply toner.

However, even if there is sufficient toner in the developing device 11, due to its structure, immediately after the toner stirring member 22 passes over the sensor surface, the toner temporarily disappears on the sensor surface, as shown in FIG. 3 (4). Then, the toner detection sensor 23 temporarily oscillates (1) at a time (T) when the toner stirring member 22 makes one revolution. Therefore, it is difficult to judge the toner end state based on the presence or absence of oscillation of the toner detection sensor, and it is also possible that too much toner is supplied due to erroneous detection, or that the drive motor of the toner supply roller is driven unnecessarily. It's the economy.

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus that can eliminate such problems and accurately perform toner end detection and toner supply.

(Structure and Operation) In order to achieve the above object, the present invention includes a developing device in a toner cartridge, and a roller that supplies toner from the toner cartridge and a sensor that detects the presence or absence of toner in the developing device. The toner supply roller is coupled to a drive motor via a clutch mechanism, which compares the output of the toner detection sensor with a predetermined value and turns on the clutch mechanism when the output of the toner detection sensor is large.
The toner is supplied for a certain period of time, and after being supplied for a certain period of time, the toner is checked by a toner detection sensor, and if it is determined that there is no toner again, a control section is provided that displays toner end.

In the present invention, when the amount of toner decreases within the time T of one rotation of the toner stirring member, the oscillation time t of the toner detection sensor within the time T becomes longer. is counted and compared with the time tA or pulse number nA that indicates a predetermined value indicating no toner, and when t>tA or n>nA, it is determined that there is no toner and the clutch mechanism for the toner supply roller is turned on. Then, the toner supply roller is rotated, and toner is supplied from the toner cartridge to the developing device. After being supplied for a certain period of time, a toner detection sensor checks the toner inside the developing device, and if it is determined that there is no toner, it is determined that the toner has run out, and the toner cartridge kit replacement is indicated and processed.

(Embodiment) Figure 1 shows a block diagram of an embodiment of the present invention. In the figure, 24 is a clutch mechanism that transmits (ON) or interrupts (OFF) the power of the drive motor 25 to the toner supply roller 21, and an electromagnetic clutch or a mechanical clutch is used. 26 is the main body CPU (microcomputer), which receives the detection signal from the toner detection sensor 23, that is, as shown in FIG. 3 (4), the toner stirring member 22 (see FIG. 4).
A timer circuit 26T that counts the time t during which the toner detection sensor 23 oscillates within the time T of one rotation, or the number n of pulses corresponding to the time t, and the time tA or the number nA of pulses indicating a predetermined toner-free value. , and a comparison circuit 26C that compares the detection outputs (t or n) of the toner detection sensor and determines whether there is no toner.

Next, the operation of this embodiment will be explained with reference to the operation flowchart shown in FIG.

First, when the toner detection sensor 23 is not attached to the developing device 11, the output is at a constant L level as shown in FIG. 3(3). When this is installed, when there is toner, it will appear as shown in Figure 3 (1).
A detection signal of a certain level (H) is output as shown below, but
When there is no toner, as shown in FIG. 3 (2), a unique oscillation wave number f is oscillated.

Then, the image forming device is printing (when there is toner,
When the toner stirring member 22 passes over the toner surface, the toner detection sensor oscillates (time t) according to the amount of toner accumulated, and as the toner decreases, the toner detection sensor oscillates (time t). Time t becomes longer.

Now, when you start the laser printer, the main CPU
26 turns on the drive motor 25 via a driver (not shown) (S,). At the same time, toner detection sensor 2
For 3, detect the end of toner in the developing device II (
S2).

The detection signal from the toner detection sensor, that is, the detection signal from the toner detection sensor, that is, the
) or the number of pulses n corresponding to the time t is counted by the timer circuit 26T, and the counting output is sequentially output to the comparison circuit 26C. The comparison circuit compares it with a predetermined value tA or nA without toner, and determines whether t>tA or n>nA.
When this happens, it is determined that the toner has run out (YES in S3).
).

The main body CPU 26 sets the clutch mechanism 24 to ○NL (S.),
The power of the drive motor 25 (shown in thick line) is supplied to the toner supply port -
from the toner cartridge 10 to the developing device 1.
1. Supply of hetoner. Then, after supplying for a certain period of time (
Standby S. ), the toner detection sensor 23 detects the toner end (SG). When the main body CPU 26 determines that the toner has run out (S7: YES), turn the clutch mechanism 24 to ○.
F F l, (S.). If the laser printer is printing (S, YES), the toner end display will be displayed; if the laser printer is not printing (Sg, No), the drive motor 25 will be stopped (S...), and the toner end display will be displayed. Let's do it.

Further, if the toner end determination (S7) in the step is No, the steps S, Sg, S1 are performed. Steps similar to s. ', s. ',s,. ' processing is performed.

In the above operation, in order to improve the detection accuracy of the toner detection sensor, the status (t>tA or n>nA)
However, it may be determined that there is no toner in the developing device after a plurality of consecutive toner agitation periods T.

Note that if it is determined that there is toner (No of S),
The clutch mechanism 24 is turned OFF to stop the rotation of the toner supply roller and stop the toner supply.

(Effects of the Invention) As explained above, the present invention provides an image forming apparatus in which a toner cartridge and a developing device are separated.
This has the advantage of being able to accurately detect toner end and supply toner.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram of an embodiment of the present invention, FIG. 2 is a diagram showing the operation flowchart of FIG. 1, FIG. 3 is a waveform diagram explaining the oscillation output state of the toner detection sensor, and FIG. 1 is a sectional view showing the configuration of a laser printer as an example to which the present invention is applied. DESCRIPTION OF SYMBOLS 10... Toner cartridge, 11... Developing device, 21... Toner supply roller, 22... Toner stirring member, 23... Toner detection sensor 24...
Clutch mechanism, 25... Drive motor, 26... Main body CPU (microcomputer), 26T... Timer circuit, 26C... Comparison circuit.

Claims (1)

[Claims] The toner cartridge includes a developing device, and the developing device includes a roller that supplies toner from the toner cartridge and a sensor that detects the presence or absence of toner, and the toner supply roller is coupled to a drive motor via a clutch mechanism. , comparing the output of the toner detection sensor with a predetermined value, and when the output of the toner detection sensor is large, turning on the clutch mechanism to supply toner;
A toner end detection and toner supply device characterized in that the toner end detection and toner supply device includes a control section that performs a toner check with a toner detection sensor after being supplied for a certain period of time, and displays a toner end indication when it is determined that there is no toner again.