JPS5922069A - Toner detector of copying machine - Google Patents

Abstract

PURPOSE:To improve reliability and detection precision by composing a capacitor of electrode plates provided in a toner box and detecting a toner level from variation in its electrostatic capacity. CONSTITUTION:A couple of electrode plates 6 and 6 are fitted to the inside of a side wall of the toner box 2 while facing each other to constitute the capacitor, and lead lines 7 and 7 are led out from the electrode plates 6 and 6 respectively. The electrode plates 6 and 6 are arranged longitudinally in parallel and toner in the toner box 2 is supplied into a developer housing by the rotation of a toner dispenser roll 1 and as the amount of the toner 5 in the toner box 2 decreases, the level of the toner 5 between the electrode plates 6 and 6 drops similarly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner detection device (1) for a copying machine.

In a copying machine, as copies are made, the amount of -C toner decreases little by little, so if you want to prevent problems caused by toner shortage by displaying toner replenishment information, check the toner level in the toner box. A device is provided for detecting.

As shown in Fig. 1, a conventional device for detecting the presence or absence of toner is a vibrating toner type in which a diaphragm (3) is arranged on the side wall of a toner box (2) that has a toner dispenser roll (1) at the bottom. A sensor (4) is provided, and the vibration plate (3) is controlled by the toner (5) in the toner box (2).
) is configured to detect the remaining amount of toner (5).

However, in a detection device with such a configuration, the vibration type sensor equipped with the above-mentioned diaphragm (3) used in the detection section is expensive, and the principle of its detection operation is
This is because the accumulation of toner (5) in the toner box (2) applies surface pressure to the diaphragm (3), and this force causes the vibration of the diaphragm (3) to stop. If an abnormal surface pressure is applied to the diaphragm (3), there is a risk of damage or malfunction. Furthermore, as mentioned above, the toner level called surface pressure (2) is detected by a secondary custom order, so the setting level and the vibration plate (3)
There is a problem that it is difficult to correspond to the position of

This invention was made in view of the above points,
It is possible to detect the toner level in the toner box of a toner dispenser with an inexpensive and simple structure, and
It is an object of the present invention to provide a toner detection device for a copying machine that is free from damage or malfunction and has high accuracy.

Hereinafter, the present invention will be described based on two illustrated embodiments.

1 and 2 show an embodiment of the toner detection device of the present invention, in which a pair of electrode plates (6) forming a capacitor are provided inside the side wall of the toner box (2).
(6) are mounted facing each other, and lead wires (7), (7) are drawn out from each electrode plate (6), (6), respectively. Each of the above electric 4if boards (6), (6
) are arranged in parallel in the longitudinal direction, and the toner dispenser roll (11 of 101) supplies the toner (5) in the toner box (2) into the developer housing, and the toner dispenser roll (11) supplies the toner (5) in the toner box (2) into the developer housing. When the amount of toner (5) decreases, the level of toner (5) also decreases in the area between each of the electrode plates (6).

That is, as the range in which the toner (5) as a dielectric exists between each electrode plate (6) and (6) decreases, the capacitance of the above-mentioned capacitor changes, and this change causes the toner (5) to decrease. ) can be detected.

FIG. 4 shows an example of a circuit that detects a toner level by detecting a change in capacitance of a capacitor composed of such electrode plates (6), (6).

In the figure, C1 is a capacitor consisting of the electrode plates (6) and (6), and an AC bridge circuit with the same principle as the Wheatstone bridge is used as a circuit to detect changes in the capacitance C of capacitor C3. It is being That is, a resistor R1 is connected in parallel with the capacitor C1, and is also connected in series with this parallel circuit to a variable resistor for balance adjustment.
1 and variable resistor R2 forms one side of the bridge circuit.

The other three sides of the bridge circuit are formed by a resistor R3, a resistor R4, and a resistor R5, respectively, and a voltage of, for example, 12 VAC is applied between the connection points ac.
AC power source (8) is connected, and the connection point bd
A resistor R6 is connected between them, and a voltmeter V is connected in parallel to this resistor R6.

The capacitance C of the capacitor C1 when there is toner (5) between each of the electrode plates ((j), (6), that is, when a shortage of toner (5) is not detected is the electrode plate (6), (
If the opposing area of 6) is A, the distance between each electrode plate (6) is d, and the dielectric constant of toner (5) is 51, then C-1-... 1), and therefore, the impedance Z of the parallel circuit portion of the capacitor C1 and the resistor R1 in this case is the AC power supply (
8), where m is the angular frequency and rl is the resistance value of resistor R2, then z-(-→r1)/-! -! −・・・・・・・・・(2
)(u(:(represented as OC).

The resistance value of the above-mentioned XF balancing variable resistor R2 is adjusted so that the balance of the bridge can be obtained in such a state. The instruction is set to OV (initialized).

A circuit consisting of a resistor R7, a diode D, and a capacitor C2 is connected to the resistor R6 for rectifying and smoothing the AC voltage generated when the bridge is unbalanced. The voltage obtained by the above circuit is supplied to one input of the comparator (9), and the voltage obtained by the circuit as described above is supplied to one input of the comparator (9). A comparison voltage is applied from the connection point between resistor R8 and resistor R9, and when a voltage higher than this comparison voltage is applied to one input of the comparator (9) (2), the comparator (9) outputs as a comparison output. A high level signal is generated at the output terminal α0).In other words, the point at which this high level signal is generated is at the variable resistor R8.
As mentioned above, the toner (5
) has decreased to the level (2) at which you want to detect the lack of toner (5) (2) When the level of the comparator (9
) The resistance value is adjusted so that the comparison voltage corresponds to the magnitude of the applied voltage.

Next, the operation of the above embodiment will be explained with reference to FIGS. 5 and 6.

Now, in the toner box (2), the operator or the like should apply sufficient amount of toner (
5) is filled, and an AC voltage is applied between the connection points ac from the AC power supply (8). In this state, the area between the electrode plates (6) and (6) is covered with toner (
5) and no shortage of toner (5) is detected.As mentioned above, the variable resistor R2 is adjusted in advance so that the frills are balanced in such a state, so the resistor R6 There is no current flowing through
Therefore, the voltage between the connection point bd, that is, the terminal voltage of the resistor R6 is 0 as shown in FIG.
The terminal voltage of is also 0 as shown in Figure 5 CB+, and each '
Pressure gauges ■1 and ■2 are also indicating 0.

Therefore, since one input of the comparator (one of the inputs is smaller than the comparison voltage preset by the variable resistor R8, its output terminal 00) will be low as shown in Fig. 5 (C) + 2. It is a level signal. 'In this way, when the output of the output terminal α0) of the comparator (9) is at a low level, the toner (5) is used.
) does not change even when the toner (5) is lowered to the position of the electrode plates (6), (6), and the level of toner (5) further decreases, causing toner to disappear in the area between each electrode plate (6), (6). Even if the range in which the comparator (9) exists decreases, the comparator (9)
Unless the voltage applied to one input of the voltage exceeds the comparison voltage, the voltage remains at a low level. Therefore, until the level of the toner (5) in the toner box (2) reaches the level (1) at which you want to detect a shortage of toner (5), even if the toner (5) is fully filled (2) and the toner level is high. Even when the above toner (5
) Even if the output terminal (1 (jl) of the comparator (9) approaches the presence/absence detection level, the output of the output terminal (1 (jl) maintains a low level, so there is no risk of malfunction, and there is no risk of damage due to abnormal surface pressure. There is no such fear.

Next, in this way, the toner (5) gradually decreases to a level at which it is desired to detect a shortage of toner (5),
As shown in Figure 2, the area between the electrode plates (6) and (6) is completely filled with air. In this state, the dielectric between the electrode plates (6) and (6) is air Therefore, the capacitance MCo of the capacitor 9-01 is different from the above equation (1) if the dielectric constant of air is ε. The impedance Z of the circuit portion is also different from the above equation (2).At this time, ε, )ε. Because of this relationship, c)co is obtained from the above equations (1) and (3), and Z)Zo is obtained from the above equations (2) and (4).

Therefore, in this case, ζ2 is the impedance Z of the impedance Z mentioned above for the resistor R6. A current of a magnitude corresponding to the change in the voltage will flow, and the voltages of the resistor R6 and capacitor C2 will be in the states shown in Figures 1 (A) and (B) (2), respectively, and one of the comparator (9) Since a voltage higher than the comparison voltage is applied to the input of the
0), a high level signal as shown in FIG. 6(C) is generated. In this way, the presence or absence of the toner (5) can be detected based on the on/off signal from the output terminal 00) of the comparator (9), and as described above, the point of detecting the presence or absence of the toner (5) is can be adjusted by variable resistor R8, so accuracy can be increased.

Also, the output ψIla J' of the comparator (9)
Using the comparison output from (10), digitally calculate 1-
In addition to detecting the presence or absence of the electrode plate (6),
It is also possible to judge the toner level in an analog manner using the voltage generated across the resistor R6 within the range of the size of the surfaces . That is, the toner (5) is applied to the electrode plate (
6), (6), during the period from when it has dropped to the 1st end portion to the lower end, each electrode plate (6), (6)
) As the area where the toner (5) exists as a dielectric between the electrode plates (6) decreases, the area where the air acts as a dielectric increases.
Condensation n-c+ when the level of toner (5) drops from the top of (6) to a position corresponding to the size of area X
The capacitance Cx is εμA−5r) εa I',・C□=□
(□ ・・・・・・(5)d
d However, 0≦r≦A, and during this period, the size of the small stream flowing through the resistor R6 changes continuously in accordance with the decrease in the toner (5) level. 1), for example, by reading the voltage on the voltage side V1 (from 2), toner (51
B] The level of the toner (5) can be determined even before no detection is detected.

In addition, to show an example of constants in the circuit shown in FIG. 4, the resistance R1 is 89 kn, and the variable resistance R21 is
okrl.

Resistor R3, resistor R4 and resistance ratio are each 100 kn, resistor R6 is 50 to Ω, resistor R7 is J, Mn, EJ variable resistor R8 is to 50 to Ω, resistor R9 is 200 to Ω, capacitor C2 is LO'pF".

U,''-like, this invention provided f2 inside the toner box? Since the toner level can be detected by changing the capacitance of the capacitor (7) using the 1itjf board, it is possible to detect the presence or absence of the (7) with a simple and inexpensive device, and the reliability is high. This has the advantage of being able to increase the accuracy and increase the accuracy.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a conventional toner detection device, FIG. 2 is a longitudinal sectional view showing an embodiment of the toner detection device for a copying machine according to the present invention, FIG. 3 is a front view of the same, and FIG. 4 is a longitudinal sectional view of the same. The electrical circuit diagrams of the device, FIGS. 5 and 6, are voltage waveform diagrams for explaining the present invention, respectively. Bow description (2)... Toner box (5)...
・Toner (6), (6)... Electrode plate (8
)... AC power supply (9)... Comparator C1°゛...° Capacitor Rlr R3r R4+
R5...Resistor R6...Variable resistor
V,, V2... Voltage range Fig. 5 (A) (B) (A) (B) (C) (C)

Claims (1)

[Claims] an electrode plate provided to constitute a capacitor in a toner box of a copying machine; a circuit that applies an alternating current voltage to the electrode plate to detect a change in capacitance caused by a drop in toner in the toner box; A toner detection device for a copying machine, comprising means for detecting a toner level based on the detection output of the detection circuit.