JPH05224482A - Detecting device for photosensitive body life in image forming device - Google Patents

Abstract

PURPOSE:To more precisely decide the life of the photosensitive body of an image forming device. CONSTITUTION:An electrostatic charge device 2 which electrostatically charges the photosensitive body is constituted of a grid electrode 10 and a corona electrode 11 and a high voltage is respectively impressed on them by high-voltage power sources 18 and 17. By a control part 20, the power source 18 is controlled based on a grid voltage control signal corresponding to a photosensitive body potential signal from a potential sensor 9 and an image forming action is executed. Simultaneously, the turning-on time of the high-voltage power source is measured. The turning-on time is converted into a correction value T' by an expression defined based on relation between electrostatic charge potential and the characteristic of the life of the photosensitive body and a new integrated value is obtained by adding the value T' to an integrated value SIGMAT' until the last time. Then, when the new integrated value exceeds over a prescribed value, the life of the photosensitive body is judged to be ended and it is informed by a display means 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for charging a photoconductor with a charging device to form an electrostatic latent image,
In particular, the present invention relates to a photoreceptor life detection device suitable for accurately grasping the life of the photoreceptor.

[0002]

2. Description of the Related Art As a conventional photosensitive member life detecting method, for example, the one disclosed in Japanese Patent Laid-Open No. 62-231270 measures the operating time of a charging device and integrates the measurement results,
The life of the photoconductor was judged from the integrated value. In this type of system, when the integrated value exceeds a predetermined time, it is converted into the number of standard sheets (for example, A4 sheets) and displayed by the display means, and when the displayed value reaches a predetermined number, the photoconductor Is judged to have reached the end of its life. That is, it is intended to accurately determine the life by calculating the time when the photoconductor actually contributes to image formation.

[0003]

However, the deterioration of the quality of the photosensitive member depends not only on the charging time but also on the charging potential thereof. FIG. 4 shows the relationship between the charging potential and the life of a certain photosensitive member. The higher the charging potential, the shorter the life. In other words, it can be seen that the higher the charging potential, the faster the quality of the photosensitive member deteriorates. FIG. 3 shows the dark decay characteristics of the same photoreceptor as described above. As the environmental conditions, A and A'in the figure are temperature 2
8 ℃, relative humidity (RH) 85%, B is 22 ℃ 50% RH
C and C ′ show the dark decay characteristics at 10 ° C. and 30% RH. In the case of B, if the charging potential V2 is applied, a predetermined dark potential V _D can be obtained at the position of the developing device (time t _D ), but in the case of A, even if V2 is applied, the potential becomes higher than V _D , and In the case of C, even if V2 is applied, the potential becomes lower than V _D, so fog copy or low density copy occurs. Therefore, in the case of A, V1 lower than V2 is applied, and in the case of C, V3 higher than V2 is applied, so that a predetermined dark potential V _D can be obtained at the developing device position like A ′ and C ′, respectively. Therefore, it is necessary to adjust the charging potential.

As described above, in order to obtain stable copy image quality irrespective of the environmental conditions, the charging potentials are different, and the life of the photoconductor is different depending on the environmental conditions. Even when the environmental conditions are constant, the charging potential may be adjusted in order to match the copy image quality desired by the user. For example, when the copy density is high, the charging potential is high, and when the copy density is low, the charging potential is low. As a result, the life of the photoconductor may be shorter or longer than usual. Therefore, if the life of the photoconductor is determined by measuring only the operating time of the charging device, the life may be incorrectly determined. An object of the present invention is to provide a photoreceptor life detection device in an image forming apparatus that can more accurately determine the life of the photoreceptor.

[0005]

In order to achieve the above object, a photoreceptor life detecting device in an image forming apparatus of the present invention comprises means for measuring a high voltage application time to a charging device and a measured application time. Means for correcting according to the high voltage application condition to the charging device, means for integrating the corrected application time, means for judging the life of the photoconductor from the integrated value, and based on the integrated value and / or the integrated value And a means for displaying the judgment result.

[0006]

[Function] ON / O of high voltage power source for applying high voltage to charging device
While controlling the FF operation, the operating time of the high voltage power supply is measured, and the result is corrected according to the output condition of the high voltage power supply,
The value is integrated. When the integrated value exceeds the predetermined value, the judging means judges the life of the photoconductor and displays the result on the display means.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a schematic control block diagram of an embodiment of an image forming apparatus to which the present invention is applied, and FIG. 2 is a schematic sectional view of an embodiment of an image forming apparatus to which the present invention is applied. The photoconductor 1 is rotatably supported in the direction of the arrow shown in the drawing.
A charging device 2, a potential sensor 9, an unnecessary electric charge removing lamp 13, a developing device 4, a transfer charging device 5, a cleaning device 7, and a charge eliminating lamp 8 are arranged around the periphery of the device. The charging device 2 includes a corona electrode 11 connected to a high-voltage power supply 17 and a charge shield 12 arranged around the corona electrode 11.
A so-called scorotron charging device, which is provided between the corona electrode 11 and the photoconductor 1 and is composed of the grid 10 connected to the high-voltage power supply 18.

A control unit 20 composed of a CPU system
Includes a high-voltage power supply 17 and 18, a D / A converter 22 for sending a grid voltage control signal to the high-voltage power supply 18, and an A / D converter 21 for taking in an analog signal according to the photoconductor potential output from the potential sensor 9. Further, the display means 19 is connected to perform the processing operation described later. Although the control unit 20 controls the operation of the entire image forming apparatus, FIG. 1 illustrates only the main part relating to the present invention.

The processing operation of the control unit will be described below. 5 and 6 are flowcharts showing the processing operation of the control unit. FIG. 7 is a timing chart of the image forming operation. When the image forming operation starts, the photoconductor rotates,
An ON signal is sent from the control unit 20 to the high voltage power supply 17
The ON signal and the grid voltage control signal Vg2 are output to the DUT 8 via the D / A converter 22, and the charging of the photoconductor 1 is started. At the same time, the control unit 20 uses an internal program to
The measurement of the ON time of the high-voltage power supply is started (S100). The elapse of the predetermined time T1 is determined (S101), and after T1, the control unit 20 causes the potential sensor 9 via the A / D converter 21.
Is monitored to measure the photoconductor potential Vs (S10).
2). Then, a grid voltage control signal Vg ′ for obtaining a desired dark potential V _D at the position of the developing device 4 is obtained from the measured value Vs by a predetermined algorithm (S10).
3). This signal Vg 'is output to the high voltage power supply 18 via the D / A converter 22 (S104). After that, scanning exposure of the original image by the exposure device 3 is started, and a predetermined image forming cycle is repeated (S105).

When the image forming operation is completed (S106),
An OFF signal is output to the high-voltage power supplies 17 and 18 to terminate the charging of the photoconductor and stop the rotation of the photoconductor. This completes the measurement of the ON time of the high-voltage power supply, and the measured value T is obtained (S107). Next, the ON time T is corrected by a correction equation defined from the relationship between the charging potential and the photoreceptor life characteristic, and T'is obtained (S108). The integrated value ΣT ′ of the correction value T ′ up to the previous time is read from the RAM (S109), and the correction value T ′ obtained in S108 is added to this integrated value to obtain a new integrated value ΣT ′ (= ΣT ′ + T ′). (S110). Then, it is determined whether or not the new integrated value ΣT 'is less than or equal to a predetermined value (S111). If it is less than the predetermined value, the new integrated value is stored in the RAM and the process is terminated (S11).
4). On the other hand, when the value exceeds the predetermined value, display processing is performed to notify that the photoconductor has reached the end of its life. Therefore, it is checked whether or not the display means 19 is in operation (S112), and in the case of Yes, the new integrated value ΣT ′ or the determination result based on the new integrated value is displayed and the new integrated value Σ is displayed.
The T'is stored in the RAM and the process ends (S114). Also N
In the case of o, the display means 19 is operated (S113), and then the same processing as in the case of the above Yes is performed.

Next, in the flow chart shown in FIG.
The calculation of g ′ will be specifically described. It should be noted that a and b are constants showing the relationship between the grid voltage control signal Vg and the grid voltage VG shown in FIG. 8, c is a constant showing the relationship between the grid voltage VG and the charging potential V shown in FIG. 9, and d is shown in FIG. Time (to ~
It is a coefficient for obtaining the amount of potential attenuation during time (ts to t _D ) from the amount of potential attenuation during ts). Vs is ts-
It is the potential of V2 after the elapse of to time. When the calculation program is started, first the grid voltage VG2 is calculated by the formula (a · Vg2
+ B) (S120), and the charging potential V2 is calculated from the grid voltage VG2 by the equation (c · VG2) (S12).
1). Next, the output monitor value V _S of the potential sensor 9 and the V
2 is used to calculate the predicted dark potential V _D 'at the developing device position by the formula (V
It is calculated by s-d (V2-Vs)) (S122). Next, the difference between the target dark potential V _D at the developing device position and the dark potential V _D ′, that is, the deviation ΔV _D of the dark potential from the target value is obtained (S123), and the correction amount Δ of the grid voltage control signal Vg is obtained. V
g is calculated by the formula (V2 · (ΔV _D / V _D ') (1 / a) (1 /
c)) is obtained (S124). Next, it is judged whether V _D ≧ V _D ′ (S125). If V _D is V _D ′ or more, grid voltage control signal Vg ′ = Vg2 + ΔVg is set (S12).
6). On the other hand, if V _D is less than V _D ′, the grid voltage control signal Vg ′ = Vg2−ΔVg is set (S127).

The grid voltage VG2 obtained from the grid voltage control signal Vg2 is shown in FIG. Since a certain photosensitive member is a grid voltage which gives a charging potential V2 capable of obtaining a predetermined dark voltage V _D at 22 ° C. and 50% RH, Vg ′
= Vg2-ΔVg is the predetermined dark potential V when the temperature and humidity are higher than that.
It becomes the grid voltage control signal to obtain _D. For example,
At 28 ° C. and 85% RH, Vg ′ = Vg2-ΔVg = Vg
It is 1.

Further, Vg '= Vg2 + ΔVg is a grid voltage control signal for obtaining the predetermined dark potential V _D at low temperature and low humidity. For example, if 10 ° C. and 30% RH, Vg ′ = Vg2
+ ΔVg = Vg3. Next, the correction of the ON time T of the high voltage power supply will be described. This process is executed immediately after the image forming operation is completed.

[0014]

[Equation 1]

Here, α, β, α'and β'are constants showing the relationship between the charging potential V and the charging time until the life of the photosensitive member, as shown in FIG. For example, in FIG. 4, the charging potential V
T _LIFE at 3 = 1200V is 0.8 times (8 when V2 = 1000V).
0/100). In other words, the charging time at V3 = 1200V is 1.2 times the charging time at V2 = 1000V.
It is equivalent to 5 times (100/80). Similarly, the charging time at V1 = 860V corresponds to about 0.952 times (100/105) the charging time at V2 = 1000V.

The above correction formula is a formula obtained for a photoconductor having the characteristics shown in FIG. 4. If the charging potential and the photoconductor life characteristic are different, the correction formula is also different. In this embodiment, when the integrated value exceeds a predetermined value, it is displayed on a display means such as an LED lamp on the operation panel. The display means is not limited to the above-mentioned configuration, and a message is displayed on the message display, or a unit including the photoconductor is provided with a mechanical counter to convert the integrated value as it is or to the number of copies of standard paper (for example, A4 paper). The configuration may be such that the displayed value is displayed. Further, the integrated value data may be transmitted via a communication line such as a telephone line and displayed on a display means of a data collection processing / control device such as a computer at a remote place. Also,
It goes without saying that the integrated value of the memory of the control unit 20 is cleared when the photoconductor or the unit including the photoconductor is replaced.

Next, as another embodiment, an image forming apparatus using a charging potential setting means will be described. The control unit 20 shown in FIG. 11 controls the grid voltage control signal V according to the two signals SIG0 and SIG1 output from the charging potential setting means 23.
It is configured to determine g '. In this charging potential setting means 23, for example, as shown in FIG. 12, + 5V is applied to the input terminals of the inverters 24 and 25, and each input terminal is connected by a switch SW so as to be selectively at the ground level. There is. A service person or the like connects the switch SW to the contact points 231 and 232 according to environmental conditions and user's request.
And 233 are input to the control unit 20 as the SIG0 signal and the SIG1 signal, which are the voltage levels at the output ends of the respective inverters. For example, switch SW
To the contact 231 side, the SIG1 signal becomes a high (High) signal, while the SIG0 signal becomes a low (L) signal.
ow) signal. Since the relationship of the grid voltage control signal Vg ′ with respect to the combination of the SIG0 signal and the SIG1 signal is prepared in advance, the control unit determines the grid voltage control signal Vg ′ by processing the above signals and turns on the high voltage power supply.
Output at the same time as the signal.

In the example shown in FIG. 13, the charging potential setting means 2
The grid voltage setting signal output from the grid 3 is directly input to the high voltage power supply 18, and the grid voltage having a predetermined value is applied to the grid 10.
It is configured to be applied to. In addition, the control unit 20
The grid voltage setting signal is taken in via the / D converter 21 and recognized as Vg '. The charging potential setting means 23 is composed of a variable volume VR as shown in FIG. 14, for example. According to this embodiment, a service person or the like can variably adjust the grid voltage control signal according to environmental conditions or user's request.

When the charging potential setting means is used, T1 = 0 in the correction formula for the high-voltage power-ON time T. In the above embodiments, the charging device is a scorotron, and the high voltage power supply ON time is corrected under grid voltage conditions. However, the present invention is not limited to this, and the photosensitive member charging potential and a certain value are set. It may be configured such that the correction is performed under the condition of the relationship, for example, the corona current amount.

[0020]

As described above, according to the present invention, since the high voltage application time to the charging device is corrected and integrated according to the high voltage application condition, when the charging potential varies depending on environmental conditions and the like. However, the life of the photoconductor can be accurately determined.

[Brief description of drawings]

FIG. 1 is a schematic control block diagram of an embodiment of an image forming apparatus to which the present invention is applied.

FIG. 2 is a schematic sectional view of an example of an image forming apparatus to which the present invention is applied.

FIG. 3 is a diagram showing dark decay characteristics of a photoconductor.

FIG. 4 is a diagram showing a relationship between charging potential and photoreceptor life.

FIG. 5 is a flowchart showing a processing operation of a control unit.

FIG. 6 is a flowchart showing a processing operation of a control unit.

FIG. 7 is a timing chart showing the operation of the embodiment of the present invention.

FIG. 8 is a diagram showing a relationship between a grid voltage control signal and a grid voltage.

FIG. 9 is a diagram showing a relationship between a grid voltage and a charging potential.

FIG. 10 is a flowchart for obtaining a grid voltage control signal.

FIG. 11 is a control block diagram of another embodiment of the present invention.

FIG. 12 is a diagram showing an embodiment of charging potential setting means.

FIG. 13 is a control block diagram of another embodiment of the present invention.

FIG. 14 is a diagram showing another embodiment of the charging potential setting means.

[Explanation of symbols]

1 Photoreceptor, 2 Charging Device, 4 Developing Device, 5 Transfer Charger, 7 Cleaning Device, 8 Eliminating Lamp, 9 Potential Sensor, 10 Grid, 11 Corona Electrode, 13
Unnecessary charge removing lamp, 17, 18 high voltage power source, 19 display means, 20 control section, 23 charging potential setting means

Claims (1)

[Claims] 1. A means for measuring a high voltage application time to a charging device, a means for correcting the measured application time according to a high voltage application condition to the charging device, and a means for accumulating the corrected application time. A photoreceptor life detecting device in an image forming apparatus, comprising: a means for determining the life of a photoreceptor based on the integrated value; and a means for displaying the integrated value and / or a determination result based on the integrated value.