SU1341593A1 - Device for measuring potential of charged layers - Google Patents

Abstract

The invention can be used, in particular, in electrophotography for testing layers for recording optical information. The purpose of the invention is to improve the measurement accuracy. The device for measuring the potential of the charged layers contains a metal carrier rod 3 connected to the electric drive 4, on which grounded shielding strips (EPZ) 5 are fixed with probes. The top surface of the EPM 5 is covered with an insulating layer, the bottom, facing the test sample 1, is filled with a gear. The device also contains a registering device 8, contacts 9 and 11, a resistor 10, a corona electrode; 12. Test sample 1 is placed on a grounded metal plane 2. 2 Il. 72 (/) CO 4 SD: o from Shuya .;

Description

The invention relates to an electrical measuring technique and can be used in determining the potential, as well as its distribution over the surface of corona-charged discharge of THIN dielectric films and photo-semiconductor layers. In particular, the invention can be used in electrophotography for testing a layer for recording optical information.

The aim of the invention is to improve the measurement accuracy by eliminating the parasitic signal, which is discharged by the discharge of air ions on the surface of the probe.

Figure 1 schematically shows the proposed device; 2 is a shielding strip, the cross section 20.

Test sample 1 is placed on a grounded metal plane 2, above which is parallel to it a metal bearing rod 25, connected to the electric drive 4. On the rod 3, grounded shielding strips 5 are fixed with probes 6 placed on them and insulated from the shielding strips 6. the surface of the shielding strips 5 is covered with an insulating film 7, the bottom facing the specimen is filled with a gear. The recording device 8 is connected to pins 9, 35, which in turn are connected to probes 6, and are bridged by a resistor 10.- Contact 11 serves to ground the metal rod 3 to the shielding strips 5. The charge 40 of sample 1 is produced by a corona electrode 1 2 ,, stir , so that the metal rod 3 rotates between it and sample 1.

The device works as follows 45 times.

A high voltage is applied to the corona electrode 12 and test sample 1 is charged in a corona discharge field. At the same time, the metal rod 3 with the probes 6 is brought into rotation. The surface charge on sample 1 causes an electromotive force (EMF) to mix electrically through the air layers and completely neutralize the ions in the gap, between the shielding strip and the sample. The reverse side of the shielding strip, facing the corona thread, is covered with an insulating film. This avoids unnecessary loss of ions in the gap. The corona electrode is a shielding strip. In addition, the presence of an insulating film makes it possible to bring the corona source close to sample 1, i.e. increase the efficiency of the charging device. We offer designs

allows to use charging devices of any type (corotron, needle electrode, etc.) and change their position relative to sample 1 at will. The current passing through resistor 10 is fixed through the integrator by a recording device, an oscilloscope 8. The charge induced on the probe is determined by the ratio

q .ES,

where E is dielectric constant

air; 6o 8.86-0f / m;

E - tension sex; S is the probe area. The potential of the probe is determined by the formula

- ..

where C is the probe capacitance relative to

sample 1. At the same time

n -1

where Vg is the potential of sample 1;

h is the distance from probe 6 to sample 1.

It follows that the current in the input circuit of the recording device B

dl

 dt

RCii

dVs

dt

where R is the resistance of the resistor 10, i.e. the magnitude of the signal from the probes 6 static induction. When moving, 55 is proportional to the linear speed of the tall rod 1 in the direction of the probes 6 and inversely proportional to the arrows indicated in FIGS. 1 and 2, the distance from the probes 6 to sample 1. On the teeth, turbulence of the potential arises. prior to calibration of the device and

intensive mixing of air layers and complete neutralization of ions in the gap between the shielding strip and the sample. The reverse side of the shielding strip, facing the corona thread, is covered with an insulating film. This avoids unnecessary loss of ions in the gap. The corona electrode is a shielding strip. In addition, the presence of an insulating film makes it possible to bring the corona source close to sample 1, i.e. increase the efficiency of the charging device. We offer designs

allows to use charging devices of any type (corotron, needle electrode, etc.) and change their position relative to sample 1 at will. The current passing through resistor 10 is fixed through the integrator by a recording device, an oscilloscope 8. The charge induced on the probe is determined by the ratio

q .ES,

where E is dielectric constant

air; 6o 8.86-0f / m;

E - tension sex; S is the probe area. The potential of the probe is determined by the formula

- ..

where C is the probe capacitance relative to

sample 1. At the same time

n -1

where Vg is the potential of sample 1;

h is the distance from probe 6 to sample 1.

It follows that the current in the input circuit of the recording device B

RCii

dVs

dt

313

continue to be unchanged. For calibration, a reference metal plate is placed instead of the sample to be tested. The plate is supplied with a constant voltage of the same polarity as the potential applied to the layer under study. A signal is sensed from probes 6, the amplitude of which is proportional to the voltage on the reference plate, and a calibration curve is used to determine the potential of the layer under study. The calibration curve gives a linear relationship between the potential applied to the reference plate and the magnitude of the signal, as recorded by the recording device.

3

Claims (1)

Invention Formula A device for measuring the potential of charged layers containing a corona electrode located above the test object, and a measuring unit containing at least one probe placed on a grounded shielding strip driven by an electric drive, the probe being isolated from the shielding strip and electrically connected to the input a recording device, characterized in that, in order to improve the accuracy of measurement The scientific research institute, the surface of the shielding strip, facing the measured Layer, is made gear, and the opposite surface is covered with an insulating layer. (rig 2