JPH0474702B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic copying machine that controls image formation by detecting the surface potential of a photoreceptor.

In a conventional electronic copying machine, a conductive substrate of a photoreceptor having a photoreceptor layer formed on the surface of the conductive substrate is grounded, and the electric charge imparted to the surface of the grounded photoreceptor is detected by a detection means arranged opposite to the photoreceptor. The image formation is controlled based on the detected surface potential of the photoreceptor. However, the detection means needs to be calibrated depending on the performance of the photoreceptor and changes over time. Therefore, in JP-A-55-33169 and JP-A-56-95255, a high-voltage power supply that supplies a predetermined calibration voltage for calibrating the detection means and a display that displays the detected value are incorporated. The electronic copying machine that has been In such conventional examples, the following method is adopted as a calibration method.

(1) For each calibration, remove the recording medium from the copying machine, attach a separate calibration electrode, and perform calibration using this calibration electrode.

(2) Attach the calibration electrode onto the recording medium.

(3) Move the potential detector to the external calibration electrode.

However, with method (1) above, it takes time to attach and remove the recording medium, and the position of the newly installed calibration electrode and the removed recording medium are not necessarily the same, so the surface potential of the photoconductor is detected. This has the drawback that an error occurs in the distance between the actual use of the electronic copying machine, which controls image formation, and the calibration time, when the detection means is calibrated, making highly accurate calibration impossible.

In addition, method (2) had drawbacks such as adhesive and the like adhering to the recording medium when attaching the calibration electrode to the recording medium, staining the recording medium.

Furthermore, method (3) requires a moving mechanism to move the potential detector to the calibration electrode provided externally, which makes the mechanism complicated and, like method (1), requires a moving mechanism to move the potential detector to the calibration electrode provided outside. This method has disadvantages such as the difficulty of highly accurate calibration due to errors caused by the

The present invention has been made with the aim of eliminating such conventional drawbacks, and is an electronic copying machine that detects the surface potential of a photoreceptor to control image formation, and is capable of calibrating a potential detector during actual use of the electronic copying machine. This allows highly accurate calibration work to be performed in a short time.

An embodiment of the present invention will be described below in detail with reference to the drawings. In the figure, 1 is the main body of an electronic copying machine, and 2 is a drum-shaped photoreceptor housed in the main body 1, which is rotated by a drive system (not shown). It is attached to the rotating shaft 3 via an insulating flange 4. 5 is the photoreceptor 2
A high-voltage power source 6 is applied to the charger that charges the surface of the device. Reference numeral 7 denotes a potential detector for detecting the surface potential of the photoreceptor 2. The surface potential detected by the potential detector 7 is amplified by an amplifier 8 and then output to a measurement terminal 9, and is connected to the measurement terminal 9 during calibration. In addition to operating the voltmeter 10, the detection sensitivity of the potential detector 7 is determined by the calibration variable resistor 1 provided in the amplifier 8.
1, it can be adjusted.

On the other hand, reference numeral 12 denotes a slip ring provided on the end surface of the photoreceptor 2, and this slip ring 12 is connected to a contact piece 13a of a calibration changeover switch 13. The calibration changeover switch 13 has a contact 13b grounded to the horizontal frame 1a of the main body 1 and a contact 13c connected to the calibration voltage generator 14, and controls image formation by detecting the surface potential of the photoreceptor. When doing so, the contact piece 13a is connected to the contact 13b side,
The photoreceptor 2 is grounded to the machine frame 1a side, and during calibration, the contact piece 13a is connected to the contact 13c side, so that a calibration voltage can be applied to the photoreceptor 2, and the calibration voltage is Measurement terminal 15
It can be read by a voltmeter 16 connected to.

Therefore, when calibrating the potential detector 7, the voltmeters 10 and 16 are connected to each measurement terminal 9 and 15, and then the contact piece 13a of the calibration changeover switch 13 is connected to the contact point 13c.
Connect to the side. As a result, pressure is applied to the photoreceptor 2 in a calibrated manner from the calibrated voltage generator 14 . Next, in this state, adjust the calibration variable resistor 11 of the amplifier 8 so that the indication on the voltmeter 10 becomes the reference value, and after adjustment, switch the calibration changeover switch 13.
Connect the contact piece 13a to the contact 13b side to connect the photoreceptor 2.
is grounded, and voltage type 1 is connected to each measurement terminal 9, 15.
Just remove 0 and 16.

As described in detail above, this invention allows the calibration of the potential detector to be carried out in the actual operating state of an electronic copying machine that detects the surface potential of the photoreceptor to control image formation. Compared to those that are calibrated manually, there are no positional errors, making it possible to perform highly accurate calibrations, and because there is no need to attach or detach calibration electrodes, the calibration work can be completed in a short time and easily. . In the embodiment, calibration was performed by connecting a voltmeter to the measurement terminal, but the present invention is not limited to this.
A display device for displaying detected values may be built-in.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, with FIG. 1 being an overall configuration diagram and FIG. 2 being an end view of a photoreceptor. 2 is a photoreceptor, and 7 is a potential detector.

Claims (1)

[Claims] 1. Photoreceptor 2 with a photosensitive layer formed on the surface of a conductive substrate
A ground potential supply means 1a that supplies a ground potential to the conductive substrate of the photoreceptor 2; A potential detector 7 that detects the surface potential of the photoreceptor 2; An adjustment means that adjusts the output of the potential detector 7. An electronic copying machine that controls image formation based on the output of the potential detector 7, comprising: a calibration voltage generating means 14 that generates a calibration voltage when adjusting the output of the potential detector 7; An electronic copying machine characterized by comprising means for selectively applying the ground potential of the ground potential supply means 1a and the calibration voltage of the calibration voltage generation means 14 to the conductive substrate of the photoreceptor 2.