JPS59129876A - Electric discharge control device of recording device - Google Patents

Abstract

PURPOSE:To eliminate the necessity of a special power source for operating an error amplifier by utilizing the voltage applied to an ionic current control member for a power source supplied to the error amplifier. CONSTITUTION:Voltage VG applied to a grid is divided and detected by resistances R1, R2 connected between a grid 3 of a scorotron 2 and a ground, and a difference between this divided voltage and set voltage VS is amplified by error amplifiers AMP1, AMP2, and applied to the base of a transistor (TR) connected between the grid 3 and a ground, by which the voltage VG applied to the grid 3 is kept constant. The VG can be varied by varying the set voltage VS. Also, the voltage applied to an ionic current control member can be utilized for a power supply to the error amplifier, therefore, a special power source becomes unnecessary.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge control device for a recording device that maintains a constant voltage applied to an ion flow control member affected by an ion flow from an electrode.

Incidentally, the term "grounded" in this specification may be actually grounded or may be connected to the housing of the recording device.

In the following description, a case will be described in which an electrophotographic copying device is used as a recording device and a scorotron grid is used as an ion flow control member.

A conventional example is shown in FIG. 1 and FIG. 2.

In FIG. 1, a varistor VD is connected between the grid 3 and the ground.
(or a Zener diode), even if the voltage of the high-voltage power source 1 exceeds a predetermined voltage and the ion flow from the charged electrode 2 increases and the voltage VC applied to the grid 3 increases, the voltage VC applied to the grid 3 increases. The voltage VC was kept constant. It is true that this method is low cost and highly stable. However, in the case of an electrophotographic copying apparatus, the charging characteristics of the photoreceptor 41 change due to temperature changes, fatigue, etc. Therefore, if the voltage VC applied to the grid 3 is fixed as shown in FIG. It has the disadvantage of not being able to compensate for changes in characteristics. That is, after the photoreceptor 41 becomes fatigued as the number of copies is increased, the charged potential of the photoreceptor 41 decreases even if the discharge ion flow is constant.

A conventional example for solving such drawbacks is shown in FIG. By connecting a high-voltage stabilized power source 11 to the grid 3, the voltage applied to the grid 3 is made variable in accordance with changes in the charging characteristics of the photoreceptor 41. However, the disadvantage is that the device itself becomes large. Furthermore, unless the output impedance of the high-voltage stabilized power source 11 is made sufficiently low, the output pressure of the voltage stabilized power source 11 will not be constant due to the flow of current from the grid 3. In other words, a high-voltage stabilized power supply with low output impedance is required, and such high-voltage stabilized power supplies are expensive and unsuitable for making actual equipment. A discharge control device for a recording device that eliminates the conventional disadvantages of not being able to compensate for changes in the charging characteristics of a photoreceptor or of being large and expensive has been submitted by the present applicant in a patent application filed on the same date. There is.

In this invention, a variable impedance element is connected between an ion flow control member and a ground side, and an error amplifier detects the difference between the voltage applied to the ion flow control member and a variable set voltage. The variable impedance element is controlled based on the signal. Such a simple configuration eliminates the conventional disadvantages of not being able to compensate for changes in the charging characteristics of the photoreceptor, or that the device is large and expensive. An object of the present invention is to provide a discharge control device for a recording device in which the applied voltage can be freely set and kept constant.

The present invention will be explained with reference to FIGS. 3 to 5.

First, the basic principle is shown in Figure 3. This is connected between the variable impedance element vz vigrid 3 and ground,
The control circuit 5 changes the impedance of the variable impedance X and VZ so that the voltage applied to the grid 3 becomes one foot. According to this basic principle, a high-voltage power supply is not required in terms of circuitry, and the voltage applied to the grid 3 can be set to any value by the control circuit 5.

Next, FIGS. 4 and 5 show an embodiment of the present invention. Note that this is an example applied to a device for negative charging. A resistor R+ connected between the grid 3 of the scorotron 2 and the ground,
The voltage VG applied to the grid is divided and detected by R4, and the difference between the divided voltage and the set voltage ys is amplified by error amplifiers AMPI and AMP2, and the transistor Tr connected between the grid 3 and the ground is amplified. By applying the voltage VC to the base of the grid 3, the voltage VC applied to the grid 3 is kept constant.

Therefore, the set voltage v! By changing l, the voltage VG applied to the grid 3 can be changed. Of course, it is also applicable to a device for regular 4i9-power. In that case, an NPN type transistor may be used as the transistor Tr, and the polarities of the base preservation diode D and the set voltage V8 may be reversed. Here, a scorotron grid is taken as an example of the ion flow control member, but it may also be a back plate of a charged electrode or a screen electrode. Although a general bipolar transistor is used as the variable inopedance element, an FET, a phototransistor on the output side of a photocoupler, or a CdS transistor may also be used.

Here, the set voltage vll is made semi-fixed by a variable resistor VR. However, it has been further developed to detect the potential, temperature, fatigue, etc. of the photoreceptor, and set the voltage V@ according to the detected values.
Of course, by changing Y and controlling the voltage VG7 applied to the grid 3, the potential of the photoreceptor can be stabilized. The present invention is very convenient in making the charging potential variable based on various conditions in this way.

FIG. 5 shows grid 3 and transistor T in FIG.
It is a thing with varistor VD and Y connected between it and r. In this method, the voltage vA applied to the varistor VD2VC is constant, and the voltage VG applied to the grid 3 is divided by the varistor D2 and the transistor Tr, so the voltage VT applied to the transistor Tr is discharged. Therefore, the variable range of the voltage VC applied to the grid 3 is narrower than in the case of FIG. 4, but this has no effect at all compared to the change in the charging ability of the photoreceptor. Therefore, there is an advantage that a low-cost transistor Tr'4 having a low collector breakdown voltage can be used. When an OPC photoreceptor is actually used, it is sufficient to set the voltage applied to the varistor VD2 to about 4 aicV:l and to vary the voltage applied to the transistor Tr from about 0 to 100 [V] as the supply value.

The present invention relates to an improvement of the discharge control device for a recording device as described above, and is characterized in that the voltage applied to the ion flow control member is used as the power supply to the error amplifier.

An embodiment of the present invention is shown in FIG. 6 and FIG. 7, respectively.

In FIG. 6, error amplifiers A1'1iP1 . There is an advantage that the VG applied to the grid 3 can be used as the power supply v", v- supplied to AMP2. A resistor R3 and Zener diodes ZD1 and ZD2Y are connected in series in this order between the grid 3 and the ground. R9 and Zener diode ZD.

Connect the contact to the negative power supply terminal - of the error amplifier AMPI and AMP2. Also Zener diode ZD...
Connect contact B of ZD2 to the non-inverting input terminal of error amplifier AMPI and AMP2 to offset it from the midpoint potential. Error amplifier A
M.P.I.

The positive power supply terminal V+ of AMP2 is grounded. This experiment Te1. t, tsue f--gui, t! --To ZD, ,ZD,
Since the voltage of 12 [V] was used, the potential of point A is -24 [V], the potential of point n is -12 [V], and -1
The error amplifiers AMPI and AMP2 operate based on 2[V]. Also, grid 3 and transistor Tr
It is of course possible to lower the withstand voltage of the transistor Tr by connecting a varistor between the transistor Tr and the transistor Tr.

In FIG. 7, the positive power supplies for the error amplifiers AMPI and AMP2 are supplied externally, and the negative power supply V- is supplied using the voltage VGY applied to the grid 3. Between the grid 3 and the ground resistor and Zener diode ZD,'
Connect in series in Y order, resistor and Zener diode ZD
, are connected to the negative power supply terminals V- of the error amplifiers AMPI and AMP2. In general, many of the control units of electrophotographic copying machines operate with a single positive power supply of +5 (V) or +10 (V), so in fact, iC! ? It is suitable for incorporation into photocopying equipment. Also in this case, it is of course possible to lower the withstand voltage of the transistor Tr by connecting a varistor between the grid 3 and the transistor Tr.

In the above embodiments, the present invention is applied to an electrophotographic copying apparatus VC, but it is of course applicable to other recording apparatuses W.

As described above, the present invention relates to the discharge-side η11 device of a recording device, and uses the voltage applied to the ion flow control member to supply power to the error amplifier, so that a special power supply is not required to operate the error amplifier. The present invention provides a discharge control device for a recording device that does not operate.

[Brief explanation of drawings]

1 and 2 show a conventional example. An embodiment of a discharge control device to which the present invention is applied is shown in FIGS. 3 to 5. An embodiment of the present invention is shown in FIG. 6 and FIG. 7, respectively. 1... High voltage power supply 2... Charger (scorotron) 3... Grid 4... Image holder 41...
Photoreceptor 42...Base 5...Control circuit
11... High voltage stabilized power supply VD, , VD2.
... Varistor VG ... Voltage applied to the grid (grid voltage)
VZ...variable impedance element AMP1. A
MP2...Error amplifier Tr...Transistor D...Base protection diode VR...Variable resistor Vs...Set voltage R+
, R2, Ra, 'R+...Resistance VA...
Voltage VT applied to varistor VD, ...transistor Tr [voltage applied ZD, , ZD2. ZD,
... Tuner diode agent W Kuwa, Mi Iwa

Claims (1)

[Scope of Claims] 1) An ion flow control member that is affected by the ion flow from the electrode, a variable impedance element connected between the ion flow control member and the ground side, and the ion flow control member and an error amplifier for detecting a difference between the voltage applied to the ion flow control member and a set voltage and applying a signal of the difference to the variable impedance element, and adjusting the voltage applied to the ion flow control member in accordance with the set voltage. A discharge control device for a recording device that maintains a constant voltage, wherein a voltage applied to the ion flow control member is used as a power supply to the error amplifier. 2) The device according to claim 1, wherein a scorotron grid, a back plate of a charged electrode, or a screen electrode is used as the ion flow control member. 3) As the variable impedance element, each bipolar transistor or FET, or a phototransistor, cas, or s'i on the output side of a photocoupler is used. equipment. Claim 1 characterized in that an ode is connected.
The apparatus according to items 1 to 3.