JPS5848068A - Method for measuring dielectric constant of photosensitive layer without contacting - Google Patents

Abstract

PURPOSE:To measure the dielectric constant of a photosensitive layer non- destructively without contacting by means of the surface potential before and after corona charging, the current flowing in ground potential, etc. CONSTITUTION:The surface potentials V2, V1 before and after charging of a photoreceptor 4 at a peripheral speed U by a corona charger 6 are read with probes 9, 11 and electrometers 10, 12; at the same time, the average value If obtained by dividing the current flowing in ground potential by the width L in the axial direction of the photoreceptor 4 while the photoreceptor 1 makes one turn is read with a DC ammeter 15. If alpha=If/(V2-V1) is calculated from these read values, dielectric constant epsilon=LXalpha/(epsilon0XU) is determined, and the dielectric constant epsilon of the photoreceptor is measured non-destructively without contacting. (epsilon0 is the vacuum dielectric constant of the photoreceptor.)

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for non-contact measuring the dielectric constant of a photosensitive layer of a photoreceptor for a dry copying machine.

Recently, demands for high sensitivity, long life, and low fatigue have increased for photoreceptors for dry greeting machines, and selenium, which is a typical inorganic photoconductor, is being used by alloying it with other elements, such as tellurium. At the same time, organic photoconductors are becoming more sensitive. To evaluate these photoconductors, it is essential to measure the dielectric constant of the photosensitive layer in order to clarify the inherent charge acceptance and sensitivity. The photoreceptor from which this measurement sample was taken can no longer be used, and in order to avoid this, Either way, it is uneconomical because an extra measuring part must be provided.If the dielectric constant could be measured without contact, this waste would be avoided (
be able to.

That is, an object of the present invention is to provide a method for measuring the dielectric constant of a photosensitive layer of a photoreceptor for a dry type copying machine in a non-destructive and non-contact manner.

The first method is to fix the photosensitive layer on the photosensitive member that is traveling at a constant speed (it is charged by a corona charger (1111), and the surface potential of the photosensitive layer immediately before and after charging is changed to the ground potential through the photosensitive member. This can be achieved by determining the dielectric constant from the current, the thickness of the photosensitive layer, and the traveling speed of the photosensitive member.

The present invention is based on the following principle. Now near the surface of the photosensitive layer of the photoreceptor (
The corona voltage Vc that exceeds the corona starting voltage vO for the metal M
When the photosensitive layer is charged by applying corona discharge and the photosensitive member is grounded, the current density Tc flowing through the photosensitive member becomes Ic.
=A (Vc-Vs) (V-Vs-Vo)
I'm so busy. In this case, (6) is the surface potential of the photosensitive layer.

Assuming that the thickness of the photosensitive layer is L1, the galvanic constant is ε, and the true dielectric constant is 60, the capacitance per unit area of the photosensitive layer is ego/L, so if we ignore the leakage current on the surface of the photosensitive layer. Established.

In FIG. 1, a photoreceptor having a photoreceptor layer 2 made of selenium, for example, on a metal substrate 1 is moved at a constant speed in the direction of the arrow as in a copying machine, while a corona charger 3 on a fixed side is being moved.
When charging with , the charged area is limited to a certain width. Assuming that the surface potential at point 0 immediately before a point on the photosensitive layer reaches the charged area is Vl, and the surface potential immediately after leaving the area is 2, the current If flowing into the grounded metal substrate 1 is I.
f = I Icdx (2) Where, If in equation 2) is the current per unit length in the direction perpendicular to the direction of travel of the photoreceptor when the current density distribution in that direction is uniform.

Here, V is the traveling speed of the photoreceptor.

That is, the current flowing into the photoreceptor is proportional to the surface potential difference before and after the photoreceptor is exposed to the corona shower.

From equation (4), Lα/l =gy Therefore, ε can be determined from the slope of the relationship curve between Lα/go and V.

FIG. 2 shows the arrangement of a device for measuring the dielectric constant of the photosensitive layer of a photosensitive drum according to an embodiment of the present invention. ◎While rotating the photosensitive drum 4, which is the photosensitive member to be measured, at a constant circumferential speed V, a DC high-voltage power source 5
It is charged by a corona charger 6 connected to. Before being charged, the drum 4 is charged with a static eliminator 8 connected to an AC high voltage power source 7.
Alternatively, after removing the surface charge using a photostatic eliminator, the surface potential v1 just before charging is measured using a surface potentiometer 10 using a probe 9, and the surface potential v2 immediately after charging is measured using a probe 11 as a surface potential 'e'. Measure by total 2. Also, the average value If of the value obtained by dividing the current flowing into the photoconductor during one rotation of the photoconductor from the start of charging by the width of the photoconductor in the axial direction.
Read from the DC ammeter 15VI connected between the drum 40 rotating shaft 14 and the earth potential. Using these values, α-I
f/(Vz-Vz) is calculated, and the separately measured thickness of the photosensitive layer, peripheral speed V of the drum, and vacuum dielectric book #0 are obtained. ε
To accurately determine the value of , change the circumferential speed V, draw a straight line showing the relationship between L"/ε0 and V as shown in Figure 3, and find the dielectric constant ε from the slope of the straight line. 3. In the illustrated example, g of the selenium photosensitive layer is 9.045.

As described above, according to the present invention, the dielectric constant of the photosensitive layer of the photosensitive member can be measured without contacting the photosensitive member from the surface potential before and after corona charging and the current flowing through the photosensitive member to the ground potential. (5) It becomes possible to control the quality of the photoreceptor or evaluate the photoconductive material of the photosensitive layer without damaging the product photoreceptor.

[Brief explanation of the drawing]

FIG. 1 is a detailed explanatory diagram of the present invention, FIG. 2 is a layout diagram of a measuring device according to an embodiment of the present invention, and FIG. 3 is a diagram showing Lα/l versus circumferential speed V according to an embodiment of the present invention. FIG. 4... Photoreceptor, 6... Corona charger, 9.11...
-Surface potential measurement probe, 10, 12...Surface potential meter, 15...DC ammeter, V...Peripheral speed. (6) Figure 1 Figure i2 Figure 73 Circumferential speed v (om/, s)

Claims (1)

[Claims] 1) The photosensitive layer on the photosensitive member traveling at a constant speed is charged with a fixed copier charger, and the surface potential of the photosensitive layer immediately before and after charging, and the current flowing through the photosensitive member to the ground potential,
A non-contact reading rate measuring method for a photosensitive layer, which is characterized in that the rust rate is determined from the thickness of the photosensitive layer and the 7 degrees of travel of the photoreceptor.