JPH0646328B2 - Electrostatic recording device and electrostatic recording device control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention detects the surface potential on a photoconductor in an electrostatic recording device such as an electrophotographic copying machine, and controls the charge amount based on the detection result. The present invention relates to an electrostatic recording device and a method of controlling the electrostatic recording device.

[Prior art]

FIG. 1 shows that the surface potential of the electrophotographic photosensitive member 2 is controlled by using the surface electrometer 1 in the electrophotographic copying machine. The surface potential of the electrophotographic photosensitive member 2 is measured by the fixed surface potential detection unit (probe) 11, and a potential measuring circuit is provided.
After the surface potential of the electrophotographic photosensitive member 2 is determined at 12, the control unit 3 changes the voltage charged by the charger 5 that performs corona charging on the surface of the electrophotographic photosensitive member 2, and the surface on the electrophotographic photosensitive member 2 is changed. The electric potential is kept constant.

FIG. 2 shows, as an example of the surface potential detecting section, a vibration capacitance type surface potential detecting section 11 in which the electrode 111 is shielded by a shield cover 112 and the chopper 113 is mounted on the chopper 113. This is performed by applying electric vibration to the voltage oscillator 114 that is present. This surface potential detector
Reference numeral 11 denotes a photoconductor 2 which is a potential measurement surface and a probe front frame 115.
And the measurement is performed with an interval d.

The output voltage of such an AC conversion type surface electrometer 11 is the third
It is proportional to the measured voltage as shown in FIG. FIG. 3 (a) shows the relationship between the surface potential of the surface to be measured and the output voltage of the electrometer, and the proportional constant of both changes greatly depending on the distance d between the surface to be measured and the probe front frame. Is shown.

Further, FIG. 3 (b) shows the relationship between the surface potential tested by putting the sensor and the circuit in a constant temperature bath of 0 ° to 50 ° C and the output voltage of the electrometer, and the proportional constants of both change with temperature. .

Therefore, the surface potential cannot be immediately obtained from the output voltage of the electrometer. In order to obtain this proportional constant, aluminum tape is wrapped around the photosensitive drum, which is the surface to be measured for potential, and a constant voltage is applied to this, so that the output of the electrometer at this time becomes a specified value. Therefore, when the probe is replaced or when the probe is contaminated with toner and the sensitivity changes, the adjustment is required again, which is advantageous in that the cost is low, but it is not practical.

Such a distance-dependent electrometer is one in which the probe case is connected to the ground, and a voltage that is proportional to the potential of the potential measurement surface is generated at the electrode. In order to avoid such inconvenience, a voltage approximately equal to the measured surface potential is fed back to the measurement probe so that the difference between the surface potential and the voltage applied to the probe is always zero. -A method called a negative feedback method for controlling has been devised and put into practical use. In this method, the output voltage becomes independent of the distance between the measuring probe and the measuring member, and the negative feedback is applied even if the sensitivity of the probe changes, so that the change in the output voltage can be regarded as substantially zero.

That is, the electrometer called this distance compensation type is connected to the high voltage power supply which is the reference potential of the probe in the probe case,
Since the voltage generated at the electrode has a value proportional to the difference between the potential of the surface to be measured and the potential of the probe, by feeding back this generated voltage to the high-voltage power supply, the potential of the probe case (high-voltage power supply potential) is always maintained. It is the surface potential to be measured and measures the output of the high-voltage power supply. However, this method called the distance compensation type has a drawback that the circuit is complicated and the cost is high.

[Object of the Invention]

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and an object thereof is an electrostatic recording apparatus and an electrostatic recording apparatus capable of controlling the amount of charge applied to an image carrier with high accuracy and at low cost. It is to provide a control method of a recording apparatus.

[Structure of Invention]

The above-mentioned object is "(a) an image carrier capable of holding an electric charge, (b) a charger for imparting an electric charge to the image carrier, and (c) a surface provided on the surface of the image carrier, AC non-contact surface potential detecting means for outputting a signal depending on the surface potential on the image carrier, (d) applying means for applying a variable voltage to the AC non-contact surface potential detecting means, (e) the The output signal (V ₁ ) of the AC non-contact surface potential detecting means to the image carrier to which a constant charge has been applied by the charger, the image carrier to which the constant charge has been applied, and the variable voltage are applied. The applied voltage value (V ₂ ) of the applying means for substantially zeroing the potential difference between the AC non-contact surface potential detecting means
And (g) a correction means for correcting the output signal (V) of the AC non-contact surface potential detection means based on the ratio, and (g) a signal corrected by the correction means. (V
_D )), and an electrostatic recording device for controlling the charging device, and "(a) charging device for applying an electric charge to the image carrier to charge the image carrier. In the control method of the electrostatic recording device controlling the charging device based on the output signal of the AC non-contact surface potential detecting means that depends on the surface potential on the body, (b) on the image carrier by the charging device. With a constant electric charge applied, the output signal (V ₁ ) of the AC non-contact surface potential detecting means is measured, and before and after this measurement, a variable voltage is applied to the AC non-contact surface potential detecting means. Then, a variable voltage value (V ₂ ) that makes the potential difference between the image carrier and the AC-type non-contact surface potential detecting means substantially 0 is measured, and (c) an electric charge is applied by the charger. AC non-contact surface potential detecting means for the image carrier An output signal (V), corrected based on the ratio of the output signal (V ₁₎ and said variable voltage value (V _2), controls said charger based in (d) of the corrected output signal (V _D) And a method of controlling an electrostatic recording device.

〔Example〕

The operation will be described with reference to the block circuit diagram of the present invention shown in FIG. 41 is a floating power supply for operating the electrometer, and the ground GB is separated from the ground GA of the copying machine, but when the normal potential is measured, the switch SW1 is tilted to the a side, so copying with the power supply ground It is connected to the machine ground GA. That is, the reference potential of the probe 11 and the circuit including the case becomes 0 V, and the output of the electrometer 6 is taken into the control unit 7 through the A / D converter 45. Therefore, in this state, it operates as an ordinary distance-dependent electrometer. To do.

Next, at the time of calibration, a constant current iD is applied to the charger 5 to set the surface potential of the electrophotographic photosensitive member, which is the surface to be measured, to V _D1.
To charge. At this time, the switches SW1 and SW2 are tilted to the side a, respectively, and the output V ₁ of the electrometer 6 is measured in a state where the switches SW1 and SW2 are operated as a normal electrometer.

Next, turn down the switches SW1 and SW2 to the b side, connect the ground of the electrometer to the output of the high-voltage power supply 43, and
The output of 43 is divided and connected to the A / D converter 45.
Be prepared to measure the output voltage of.

When the output voltage of the high-voltage power supply 43 is continuously changed in this state by a command from the control unit 7, the timing when the output voltage of the high-voltage power supply 43 becomes substantially equal to the surface potential of the electrophotographic photosensitive member 2 (see FIG. At t ₀ ) of a), the phase of the output voltage of the electrometer probe is inverted. FIG. 5 shows the phase inversion of the output voltage of the electrometer probe, with the horizontal axis representing the time axis.

The timing of this phase inversion is detected using the phase detector 64, and the output V ₂ of the high voltage power supply 43 at this timing is measured using the A / D converter 45. Since this output V ₂ is equal to the surface potential V _D1 on the electrophotographic photosensitive member 2, the surface potential V with respect to an arbitrary electrometer output V is expressed by the equation K = V ₂ / V _1.
D is Can be obtained by

In the above embodiment, the high-voltage power supply 43 can be shared with the developing bias power supply for the electrostatic recording device.

Further, in this embodiment, the potential is calibrated at the timing when the phase of the output of the electrometer probe is inverted. However, as is clear from FIG. 5 (c), the surface potential and the earth potential of the electrometer (the output of the high voltage power source). Since the output voltage of the probe becomes 0 V at the timing when the voltages) match, it may be detected.

According to the present embodiment described above, the distance compensation type surface electrometer is simply connected to the electrostatic recording device such as the electrophotographic copying machine equipped with the distance dependent surface electrometer by connecting the phase detection circuit and the high voltage power source. It is possible to perform the charge amount control of the electrostatic recording apparatus including the same as the charge amount control with substantially the same accuracy.

〔The invention's effect〕

As described above, according to the present invention, it is possible to provide an electrostatic recording apparatus and an electrostatic recording apparatus control method capable of controlling the charge amount with high accuracy and at low cost.

[Brief description of drawings]

FIG. 1 shows that the surface potential of the electrophotographic photosensitive member is controlled using a surface potential meter. FIG. 2 shows a vibration capacitance type probe. Figures 3 (a) and 3 (b) show the relationship between the surface potential and the output voltage of the electrometer. FIG. 4 shows a block circuit diagram of the present invention. FIG. 5 shows the output voltage curve of the electrometer probe when the output voltage of the high voltage power supply is changed. 1, 6 ...... Potentiometer, 2 ...... Electrophotographic photoreceptor 5 …… Charger, 7 …… Control unit 41 …… Floating power supply 43 …… High voltage power supply, 45 …… A / D converter 64 …… Phase detection vessel

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-56-106163 (JP, A) JP-A-55-149848 (JP, A) JP-A-58-66066 (JP, A) JP-A-60- 56265 (JP, A) JP 55-149851 (JP, A) JP 56-108964 (JP, A) JP 58-211669 (JP, A) JP-B 5-30222 (JP, B2) Japanese Patent Publication No. 2-61027 (JP, B2)

Claims (4)

[Claims] 1. An image carrier capable of holding an electric charge; (b) a charger for giving an electric charge to the image carrier; and (c) a surface of the image carrier, which is provided so as to face the surface of the image carrier. AC non-contact surface potential detecting means for outputting a signal depending on the surface potential on the image carrier, (d) applying means for applying a variable voltage to the AC non-contact surface potential detecting means, (e) The output signal (V ₁ ) of the AC non-contact surface potential detecting means to the image carrier to which a constant charge has been applied by the charger, the image carrier to which the constant charge has been applied, and the variable voltage are applied. And a means for obtaining a ratio of the applied voltage value (V ₂ ) of the applying means that makes the potential difference between the AC non-contact surface potential detecting means and the AC non-contact surface potential detecting means substantially zero, and (f) the AC non-contact Correction means for correcting the output signal (V) of the surface potential detection means based on the ratio, (g) An electrostatic recording apparatus comprising: a control unit that controls the charger based on the signal (V _D ) corrected by the correction unit. 2. The applying means is detected by detecting the timing when the phase of the output signal of the AC non-contact surface potential detecting means is inverted or the timing when the output signal of the AC non-contact surface potential detecting means is minimized. _2. The electrostatic recording apparatus according to claim 1, wherein the applied voltage value (V ₂ ) of is obtained. 3. (a) An electric charge is applied to the image carrier by the charger, and the charger is activated based on the output signal of the AC non-contact surface potential detecting means which depends on the surface potential on the image carrier. In a control method of an electrostatic recording apparatus for controlling, (b) a state in which a constant charge is applied to the image carrier by the charger; an output signal (V ₁ ) of the AC non-contact surface potential detecting means
Before and after this measurement, a variable voltage was applied to the AC type non-contact surface potential detecting means to substantially reduce the potential difference between the image carrier and the AC type non-contact surface potential detecting means. A variable voltage value (V ₂ ) to be set to 0 is measured, and (c) the output signal (V) of the AC non-contact surface potential detection means to the image carrier charged with the charger is The output signal (V ₁ ) and the variable voltage value (V
₂ ) A method of controlling an electrostatic recording apparatus, characterized in that the charging device is corrected based on a ratio thereof and (d) the charger is controlled based on the corrected output signal (V _D ). 4. The variable voltage value (V _{2) according} to the timing when the phase of the output signal of the AC non-contact surface potential detecting means is inverted or the timing when the output signal of the AC non-contact surface potential detecting means becomes minimum. ) Is obtained, the control method of the electrostatic recording device according to claim 3.