JPH0348267A - Toner end detection and toner supplying device - Google Patents

Abstract

PURPOSE:To accurately perform toner end detection and toner supply by comparing the oscillation frequency of a toner detection sensor which is counted at every interval of a constant time with set values and judging the supply and end state of toner. CONSTITUTION:A control part 26 compares the oscillation frequency (n) of the toner detection sensor 23 which is counted at every interval of the constant time with values (n1, n2, and n3) indicating toner remaining values to supply toner until n>n1 and judges the toner end state when n<n3. Then when toner deceases in amount in the time T of one turn of a toner agitation member, the oscillation time (t) of the toner detection sensor 23 in the time T becomes long, so the oscillation frequency (n) corresponding to the time is counted. Consequently, the detection of the toner end state and the 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, facsimile, and printer. (Prior Art) FIG. 5 is a sectional view showing the structure 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 the image is written upward (in the direction of arrow A) by the intermediate roller pair 5. Transported to the department. On the other hand, the surface of the photoreceptor drum 7 is charged by the charger 6, and the optical writing position [9] is charged by the optical writing optical unit 8.
The electrostatic latent image formed on the photosensitive drum 7 is developed by the developing device 1l in the toner cartridge 10 to form a toner image (visible image), which is fed by the registration roller pair 12. The image is transferred onto recording paper 2 by transfer charger l3. After the transfer, 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 the fixing unit 16 by the suction fan l5, fixed, and discharged to the stray paper tray 17. Also, 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 1L. This developing device includes a developing roller 20, a toner supply roller 21 that supplies toner from the toner cartridge 10 separated from the developing device 11 to the developing device l1, and rotates in one direction at a constant cycle to stir the toner in the developing device. The toner agitating member 22 is equipped with a toner agitation 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. 4 (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 Figure 4 (2). Based on this detection signal, the CPU of the main body determines whether there is toner or not, 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 agitating member 22 passes over the sensor surface, toner temporarily disappears on the sensor surface, as shown in FIG. 4 (3). Then, the toner detection sensor 23 temporarily oscillates (1) at the 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, causing an error. It's the economy. It is an object of the present invention to eliminate such problems and provide an apparatus that can accurately detect toner end and supply toner. (Structure and operation) In order to achieve the above object, the present invention includes a developing device in a toner cartridge, a roller that supplies toner from the toner cartridge, and a sensor that detects the presence or absence of toner. , the toner supply roller is coupled to a drive motor via a clutch mechanism, and the number n of oscillations of the toner detection sensor counted at regular intervals;
A value indicating a toner residual value preset in multiple stages (n1
, n. ...ni), n) supplies toner up to ne. The present invention is characterized in that it includes a control section that determines that the toner has run out when n<n3. In the present invention, when the toner decreases within the time T of one rotation of the toner stirring member, the oscillation time t within the time T of the toner detection sensor becomes longer, so the number of oscillations n corresponding to this time becomes longer.
On the other hand, the toner residual value nxt nut...n, (where * nx>n@H
n<n3), n) n1. When the toner reaches n (n 3), it is determined that the toner has run out and the toner cartridge is replaced. (Embodiment) Fig. 1 shows a block diagram of an embodiment of the present invention. 24 is a clutch mechanism that transmits (ON) or cuts off (OFF) the power of the drive motor 25 to the toner supply roller 2l, and an electromagnetic clutch or a mechanical clutch is used. 26 is a main body CPU (microcomputer) that transmits (ON) or interrupts (OFF) the power of the drive motor 25 to the toner supply roller 2l. The detection signal from the detection sensor 23, that is, as shown in FIG. 4 (3), the toner stirring member 22 (see FIG. 5)
A counting circuit 2 that counts the number of pulses n corresponding to the time t during which the toner detection sensor 23 oscillates within the time T of one rotation.
6K, and in this example, three stages nxv n! I n3
Comparison circuit 26 that compares the value indicating the amount of residual toner determined by the number of pulses n and determines toner supply and toner end.
G. FIG. 2 is a characteristic diagram showing an example of the number of oscillations n of the toner detection sensor within time T (vertical axis) and the remaining toner ffl in the developing device (horizontal axis). As shown in the figure, the comparison circuit 26C is set to judge the remaining amount of toner at a level corresponding to the number of pulses n, and the remaining amount of toner increases from left to right in the drawing on the horizontal axis. It shows that there are few. Next, the operation of this embodiment will be explained using the operation flowchart shown in FIG. Now, when you start the laser printer, the main CPU
26 turns on the sliding motor 25 via a driver (not shown) (S1). At the same time, toner detection sensor 2
3, the amount of toner in the developing device ll is detected (S
2).

The detection signal from the toner detection sensor 23, that is, FIG.
3) The pulse count circuit 2 calculates the number of pulses n corresponding to the time t.
6K and sequentially outputs the counting output to the comparator circuit 26C. The comparator circuit calculates three predetermined toner residual values n. , n. , n. First, level n in Figure 2
) n. (S3). If YES, the main body CPU 26 turns the clutch mechanism 24 ONL, (S,) in synchronization with the warm-up print operation, and transmits the power of the drive motor 25 (shown by the thick line) to the toner supply roller 21, n ) n. Continue supplying toner until the Then, the toner amount is detected again by the toner detection sensor 23 (S.), and the detection signal, that is, the number of pulses n corresponding to time t in FIG. 4 (3), and the toner residual value set in the comparison circuit 26G are n, is compared (n<n3) and (S
, ), If YES, the developing device ll as shown in FIG.
The toner end display/
Perform processing (S.). In other words, toner cartridge 1
Performs a 0 conversion. On the other hand, in the judgment step (S3), if nxn2 is No. n) n, is determined by the comparison circuit 26C (S.). if. If YES, the clutch mechanism 24 is turned off (S,) and the drive motor 25 is turned off.
The power to the toner supply roller 2L from the toner cartridge 1O is cut off, and toner is not supplied from the toner cartridge 1O to the developing device 1L. By the way, at the time when n ) n is determined in the above judgment step (S.), the clutch mechanism 24 is turned off (S.
). n) If the warm-up or print operation ends before reaching n1, the clutch mechanism 24 is set to ○FFL when the drive motor 25 stops, and the clutch mechanism is set to ONL when the drive motor 25 starts rotating due to the next print operation.
Then supply toner again. In this way, toner is supplied during warm-up and when the drive motor rotates during printing operations, and the amount of toner in the developing device can always be kept constant. Finally, the toner in the toner cartridge and developing device runs out, and the above n ( n ,
If this occurs, the toner has run out and the toner cartridge should be replaced. Note that the toner residual value of the above comparison circuit is judged in three stages: n, n2, and n. In order to always maintain the toner amount in a full state, it is possible to do this more precisely by increasing the number of detection stages. (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 effect of accurately detecting the end of toner and supplying toner.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a characteristic diagram showing an example of the number of oscillations of the toner detection sensor within time T and the amount of toner remaining in the developing device, and FIG. 4 is a waveform diagram explaining the oscillation output state of the toner detection sensor, and FIG. 5 is a sectional view showing the configuration of a laser printer as an example to which the present invention is applied. IO... Toner cartridge. 11・
...Developer, 2l... Toner supply roller, 22...
・Toner stirring member, 23... Toner detection sensor
24...Clutch mechanism, 25...Drive motor, 26
...Main CPU (microcomputer), 26K
... Counting 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. and compares the number of oscillations n of the toner detection sensor counted at regular intervals with values (n_1, n_2,...n_3) indicating toner residual values set in advance in multiple stages,
A toner end detection and toner supply device characterized by comprising a control section that supplies toner until n>n_1 and determines that toner is end when n<n_3.